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Rotational Motion of NH 4 + in NH 4 MnCl 3 Compared to NH 4 MnF 3 : Heat Capacity Measurements | Heat capacity measurements (6 K − 350 K) of NH4MnCl3 are reported. Two anomalies at T1 = 103.0 ± 0.3 K, due to para-antiferromagnetic ordering and at T2 = 265.6 ± 0.2 K, due to a structural change (cubic to pseudo-tetragonal) of first order character are reported. Moreover, a broad and round maximum at 180 K indicate the existence of NH 4 + rotational motion. Using a point charge model the potential barriers hindering this motion have been calculated, as well as the rotational energy level schemes, for both symmetries. In the frame of this model the observed features are explained. Moreover, a comparison to the NH4MnF3 case is consistent with the model. | We study the effects of interorbital hopping on orbital fluctuations and Mott-Hubbard metal-insulator transition (MIT) in the two-orbital Hubbard model within the extended linearized dynamical mean-field theory. By mapping the model onto an effective model with different bandwidths through the canonical transformation, we find that at half-filling, the increases of the interorbital Coulomb interaction $U^{\prime}$ and the Hund's coupling $J$ drive the MIT, and the critical $J_{c}$ for MIT increases with the lift of the inter-orbital hopping integral $t_{ab}$. Meanwhile at quarter filling and in the strong correlation regime, the system without $t_{ab}$ exhibits MIT with the decreasing of $J$, and favors the orbital liquid ground state. However, the system transits from metal to insulator with the increasing of t$_{ab}$, accompanied with the rising of the orbital order parameter. These results show the important role of the interorbital hopping in the orbital fluctuation and orbital ordering. | eng_Latn | 27,900 |
Atomic Data for He-like Tungsten | Atomic data on high-Z materials are important for impurity diagnostics due to its possible use in the next generation fusion devices including astrophysics. For this purpose, in the present paper, energies, lifetimes and wave-function compositions have been computed for all level of 1s$^2$, 1s2l,1s3l, 1s4l, 1s5l and 1s6l in highly charged He-like tungsten ion (W LXXIII). Also, we have presented the transition wavelengths, oscillator strengths, transition probabilities and line strengths for the electric dipole (E1) transitions from the levels 1s$^2$, 1s2s and 1s2p. Our reported results have been obtained using the fully relativistic GRASP code including the correlations within the $n = 6$ complex. The validity of the method is assessed through the comparison with the other results previously published. The excellent agreement observed between our new GRASP results and those obtained using different approaches confirm the accuracy of our results. | Abstract This work is concerned with the magnetic properties of Ni(NO 3 ) 2 ·2H 2 O from ( H in - T ) and ( H ap - T ) phase diagrams. From these diagrams we have obtained the values of H c (0), T N and T t . A comparison between experimental and theoretical values of T t is made, where a T t relation for a spin 1 metamagnetic model is found. | kor_Hang | 27,901 |
Three-terminal spin filter based on spin-orbit coupling in the presence of anti-dot | We have numerically investigated the spin-dependent electronic transport in a multi-terminal conductor with an anti-dot at the junction in the presence of spin-orbit coupling. It is shown that the direction of spin polarization can be flipped by changing the Fermi energy with respect to the height of anti-dot potential in a three-terminal conductor. This is understood by the interplay between spin-orbit coupling and the curvature of the potential. The spin Hall conductance in a four-terminal conductor with an anti-dot is also investigated. | The 2-D thin film equation describing the evolution of hang drops is studied. All radially symmetric steady states are classified, and their energy stability is determined. It is shown that the droplet with zero contact angle is the only global energy minimizer and the dry spot with zero contact angle is a strict local energy minimizer. | eng_Latn | 27,902 |
Early MRI findings of small bowel obstruction: an experimental study | Poster: "ECR 2012 / B-0199 / Early MRI findings of small bowel obstruction: an experimental study" by: "F. Iacobellis, D. Berritto, F. Somma, M. P. Belfiore, S. Cappabianca, A. Rotondo, R. Grassi; Naples/IT" | Abstract The fabrication of high-quality Heusler alloy films with clear martensitic transformation is a challenging issue in the field of magnetic shape memory alloys. Here, flexible Mn-rich Ni–Mn–Sn (Mn49.9Ni40.4Sn9.7) thin films are successfully synthesized by pulsed laser deposition on mica substrates using Ti as buffer layer. XRD analysis reveals that films exhibit austenitic phase with L21 structure at room temperature. The surface morphology indicates polycrystalline structure of fine grains with size of about 60 nm and smooth surface with roughness of less than 1 nm. The temperature dependent magnetization measurement clearly confirms the existence of first-order martensitic transformation. Exchange bias was observed below 70 K with maximum exchange bias field of 148 Oe at 20 K, which is attributed to the exchange coupling between the coexisting antiferromagnetic and ferromagnetic phases due to the various occupations of Mn atoms. | eng_Latn | 27,903 |
Analysis of a coupled coplanar waveguide for MMIC applications | The article presents a computational method for calculating the electric potential and field distributions in a coupled coplanar waveguide with finite electrode thickness. This method provides a simple and fast approach to the quasistatic analysis of the structures. The same structure with infinitely thin electrodes is also analyzed using conformal-mapping techniques, and excellent agreement of the results is obtained between the two methods. © 1995 John Wiley & Sons, Inc. | We report on magnetization measurements in $({\mathrm{La}}_{0.937}{\mathrm{Sr}}_{0.063}{)}_{2}{\mathrm{CuO}}_{4}$ crystals with the field either parallel or perpendicular to the c axis. A second magnetization peak (``fishtail''), interpreted as indicating a vortex order-disorder transition, is observed in both directions. Differences in the details of the fishtail anomaly in the two directions (width, temperature and time dependence, and history effects) are attributed to the anisotropy and the twin boundaries in the ab plane. The transition fields in both directions, although different in magnitude, exhibit similar qualitative behavior, namely, a strong decrease with temperature in the entire measured range. This unique behavior is explained postulating that both thermally and disordered induced fluctuations contribute to the destruction of the vortex lattice. The resulting ``pinned liquid'' disordered state is characterized by large thermal fluctuations and irreversible magnetic behavior. | eng_Latn | 27,904 |
Electronic structure of the TbMn0.33Ge2 compound: Band calculation and optical experiment | The results of the investigation of the electronic structure and optical properties of the TbMn0.33Ge2 compound have been presented. The spin-polarized calculations of the band spectrum have been performed within the framework of the local spin density approximation (LSDA) with a correction for strong correlations in the 4f shell of the rare-earth ion (the LSDA + U method). The optical constants have been measured using the ellipsometric method and a number of spectral and electronic characteristics of the compound under investigation have been determined over a wide range of wavelengths. The interband part of the experimental dependence of the optical conductivity has been interpreted using the results of the calculation of the electron density of states. | The magnetization M under temperature 1.72K in the range of magnetic field B 0‐5T and the magnetic susceptibility (MS) under magnetic field 0.1T in the temperature range 1.7 400K of the powder and crystal PbTe:Eu samples fabricated from the bulk and surface layers of the doped ingots grown from the melt by the Bridgman method are investigated. Specific magnetic properties in the Eu-doped PbTe single crystals are revealed: (i) the strong dierences between the magnetization and MS of the surface and bulk of the PbTe:Eu doped ingots; (ii) strong paramagnetism of the surface layers practically independent of T in the temperature range over 30K; (iii) the principal discrepancies between the temperature dependences of MS of the crystal matrix of powder and crystal doped samples. Possible mechanisms of the appearance of the mentioned peculiarities of the magnetic properties of dierent | eng_Latn | 27,905 |
Critical behavior in Ni0.15Cu0.15 Zn0.7Fe2O4 spinel ferrite | Abstract We report an in-depth investigation of the critical behavior in Ni0.15Cu0.15Zn0.7Fe2O4 (NCZFO) spinel ferrite synthesized via the solid-state reaction method. The structural analysis demonstrates that NCZFO belongs to the Fd 3 ¯ m space group of the cubic crystal system. The magnetic transformation in NCZFO at approximately TC = 290 K is of the second order, as per the Banerjee criteria. Employing various models, we have attempted to estimate the CP (critical parameter) values. The self-consistency of the CPs is confirmed by Widom's relation as well as the scaling hypothesis. The values of the CPs manifest that the magnetic ordering in NCZFO belongs to the Heisenberg theory in three dimensions, signifying short-range ferromagnetic interactions. The relationship between the exchange distance (J(r)) and the spatial distance (r) in NCZFO are expected to decline as J(r) ∼r−4.947. | Silicene and Graphene are similar and have $\pi$-$\pi^*$ bands. However band width in silicene is only a third of graphene. It results in a substantial increase in the ratio of Hubbard U to band width W, U/W $\sim$ 0.5 in graphene to $\sim 1$ in silicene. This enhancement, 2 dimensionality and phenomenology suggest a Mott insulator based ground state for silicene (G. Baskaran, arXiv:1309.2242). We lend support to the above proposal by showing, in an ab-initio calculation, that unlike graphene, silicene has two instabilities: i) a valence bond (Kekule) dimerization and ii) a weak two sublattice antiferromagnetic order. Presence of these instabilities, in the absence of fermi surface nesting, point to Mott localization, \textit{within the frame work of ab-initio scheme}. Substrate dependent structural reconstructions seen experimentally in silicene are interpreted as generalized Kekule bond order. | eng_Latn | 27,906 |
Efficient quenching of singlet oxygen via energy transfer to semiconducting single-walled carbon nanotubes | Singlet oxygen, 1O2(a1Δg), is efficiently deactivated by single-walled carbon nanotubes (SWNTs) having diameters in the range d ≈ 1−1.6 nm. This is evidenced by quenching of the near-infrared emission of photosensitized 1O2 in water−surfactant dispersions of SWNTs. The observed quenching rate is close to the diffusion-limited value. The smaller diameter SWNTs are found to be comparatively less active, despite the presence of metallic tube types. We therefore attribute the quenching to energy transfer from 1O2 to primarily semiconducting SWNTs having a sufficiently small band gap (d ≥ 1 nm). Remarkably, photogeneration and quenching of up to ∼109 singlet oxygen molecules per nanotube (ultimately limited by degradation of the rose bengal sensitizer) does not affect the photoluminescence and absorption spectra of SWNTs. This indicates that dispersed SWNTs are highly chemically inert toward 1O2 and provides additional support for the proposed physical (energy transfer) quenching mechanism. | We have performed high-throughput characterization of composition-spread La 1-x Ca x MnO 3 (LCMO) and Nd 1-x Sr x MnO 3 (NSMO) films, fabricated by the precursor technique, with a scanning SQUID microscope (SSM). In both films, SSM successfully observed spatial variation of magnetic field, corresponding to magnetic phase transitions with respect to chemical composition. The obtained magnetic phase diagrams basically reproduced those reported in bulk materials. However, several distinctive differences have also been noted. For instance, the region identified as a charge ordered insulator in LCMO revealed intense field, suggesting the occurrence of phase separation into ferromagnetic and non-magnetic states. These results confirm that SSM possesses sufficient analytical performance for high-throughput characterization of combinatorial magnetic libraries in composition spread form. | eng_Latn | 27,907 |
Spin-orbit coupling and electronic charge effects in Mott insulators | We derive the effective charge- and current-density operators for the strong-coupling limit of a single-band Mott insulator in the presence of spin-orbit coupling and show that the spin-orbit contribution to the effective charge density leads to novel mechanisms for multiferroic behavior. In some sense, these mechanisms are the electronic counterpart of the ionic-based mechanisms, which have been proposed for explaining the electric polarization induced by spiral spin orderings. In addition, the new electronic mechanisms are illustrated by considering cycloidal and proper-screw magnetic orderings on sawtooth and kagome lattices. As for the isotropic case, geometric frustration is crucial for achieving this purely electronic coupling between spin and charge degrees of freedom. | In this paper, we consider the second order wave equation discretized in space by summation-by-parts-simultaneous approximation term (SBP-SAT) technique. Special emphasis is placed on the accuracy analysis of the treatment of the Dirichlet boundary condition and of the grid interface condition. The result shows that a boundary or grid interface closure with truncation error $\mathcal{O}(h^p)$ converges of order $p + 2$ if the penalty parameters are chosen carefully. We show that stability does not automatically yield a gain of two orders in convergence rate. The accuracy analysis is verified by numerical experiments. | eng_Latn | 27,908 |
The Double Exchange Model at Low Densities | CFP and Departamento de F´isica, Faculdade de Ciˆencias Universidade do Porto, 4169-007 Porto, Portugal.(Dated: 2nd February 2008)We obtain the phase diagram of the double-exchange model at low electronic densities in the pres-ence of electron-electron interactions. The single particle problem and its extension to low electronicdensities, when a Wigner crystal of magnetic polarons is generated due to unscreened Coulomb inter-actions, is studied. It is argued that the Wigner crystal is the natural alternative to phase separationwhen the Coulomb interaction is taken into account. We discuss the thermal and quantum stabilityof the crystalline phase towards a polaronic Fermi liquid and a homogeneous, metallic, ferromagneticphase. The relevance and application of our results to EuB | This paper presents a study of the technical efficiency of industries in a transitional economy: China. Using data for 28 manufacturing industries across 29 provinces and the Data Envelopment Analysis approach, the technical efficiency of each industry is measured and compared across regions and provinces. The determinants of differential technical efficiency performance are analysed, with a particular focus on the impact of trade orientation and foreign investment. Trade openness is found generally to have a positive effect on technical efficiency. | eng_Latn | 27,909 |
Nonreciprocal Metasurfaces through Biasing with Circularly Polarized Waves | Spatiotemporal modulation (STM) has emerged as a promising paradigm for the development of magnetless nonreciprocal devices, but it poses significant practical challenges when sought to be implemented over structures with a large number of modulated components, such as metasurfaces. Here it is shown that this problem may be overcome in metasurfaces biased with circular-polarized waves. In particular, it is shown that this type of biasing can create modulation equivalent to angular-momentum modulation, without any complicated modulation network. Different forms of CP modulation are discussed and shown how they can lead to different nonreciprocal functionalities, including Faraday rotation, nonreciprocal amplification and isolation. | We study in this paper the properties of a two-body random matrix ensemble for distinguishable spins. We require the ensemble to be invariant under the group of local transformations and analyze a parametrization in terms of the group parameters and the remaining parameters associated with the 'entangling' part of the interaction. We then specialize to a spin chain with nearest-neighbour interactions and numerically find a new type of quantum-phase transition related to the strength of a random external field, i.e. the time-reversal-breaking one-body interaction term. | eng_Latn | 27,910 |
19F and 31P magnetic shielding anisotropies in phosphoryl fluoride | The 19F and 31P magnetic shielding anisotropies in the phosphoryl fluoride molecule have been determined from studies of the temperature dependence of the 19F and 31P chemical shifts and the anisotropic couplings in nematic solutions. Measurements of the F-P-F bond angle are reported. The possible existence of an anisotropy in the indirect P-F spin-spin coupling which is investigated does not change the values of the shielding anisotropies significantly. | The paper studies the behaviour of the Mn spin for dilute Mn in Pt as a function of temperature and applied field using the technique of nuclear orientation. In the preferentially oriented cubic polycrystalline foil a preferential nuclear spin ordering axis has been observed in the absence of an applied field. A measure of interaction of the spin with its environment has been obtained which may be modelled by a molecular field with mean value 440 G, and having a distribution in magnitude and direction. The saturation hyperfine field for Mn in Pt was found to be -365+or-15 kG. | eng_Latn | 27,911 |
Fermi Liquid in Degenerate Anderson Lattice | We investigate the Fermi liquid in the infinite- U degenerate Anderson lattice using expansion from the limit of large spin-orbital degeneracy N . By collecting all diagrams up to O ( N -2 ), we show that the imaginary part of the self-energy of the conduction electrons is given by a form proportional to (ω-µ) 2 +π 2 T 2 . We also show that the Luttinger sum rule holds up to O ( N -1 ). This implies that the literal 1/ N -expansion procedure correctly describes the Fermi liquid in the U -infinite Anderson lattice. | ABSTRACT The subject of the present investigations is a ternary system (lecithin - D2O - PAE16). The methods of the small angle X-ray diffraction and NMR were used. In the region of the water swilling lamellar structure an intermediate phase as well as a room temperature hexagonal phase at low water concentrations were observed. | eng_Latn | 27,912 |
Physiological responses at the lactate-minimum-intensity with and without prior high-intensity exercise | ABSTRACTThis study examined the physiological responses during exercise-to-exhaustion at the lactate-minimum-intensity with and without prior high-intensity exercise. Eleven recreationally trained males performed a graded exercise test, a lactate minimum test and two constant-load tests at lactate-minimum-intensity until exhaustion, which were applied with or without prior hyperlactatemia induction (i.e., 30-s Wingate test). The physiological responses were significantly different (P < 0.05) between constant-load tests for pulmonary ventilation (), blood-lactate-concentration ([La−]), pH, bicarbonate concentration ([HCO3]) and partial pressure of carbon dioxide during the initial minutes. The comparisons within constant-load tests showed steady state behaviour for oxygen uptake and the respiratory exchange ratio, but heart rate and rating of perceived exertion increased significantly during both exercise conditions, while the increased only during constant-load effort. During effort performed after high-i... | Quantum Hall edge channels at integer filling factor provide a unique test-bench to understand decoherence and relaxation of single electronic excitations in a ballistic quantum conductor. In this Letter, we obtain a full visualization of the decoherence scenario of energy (Landau) and time (Levitov) resolved single electron excitations at filling factor $\nu=2$. We show that the Landau excitation exhibits a fast relaxation followed by spin-charge separation whereas the Levitov excitation only experiences spin-charge separation. We finally suggest to use Hong-Ou-Mandel type experiments to probe specific signatures of these different scenarios. | eng_Latn | 27,913 |
Organic and inorganic hybrid nanoparticles based on iron carboxylates | Isoreticular porous crystalline MOF nanoparticle comprising a three-dimensional succession of structures corresponding to formula (I): FemOkXlLp Formula (I) in which: - Fe represents the metal ion Fe3 + or Fe2 +; - m is 1 to 4; - k is 0 to 4; - l is 0 to 4; - p is 1 to 4; - X is a ligand chosen in the group comprising OH-, Cl-, F-, I-, Br-, SO42-, NO3-, ClO4-, PF6-, BF3-, R1- (COO) n-, R1 - (SO3) n-, R1- (PO3) n-, where R1 is a hydrogen, a C1 to C12 alkyl, linear or branched, optionally substituted, n> = 1 to 4; - L is a di-, tri-, tetra- or hexa-carboxylate spacer ligand chosen in the group comprising ** Table ** | Bi3Mn4O12(NO3), in which the Mn4+ ions carry S=3/2, is the first honeycomb lattice system that shows no long-range magnetic order. Using neutron scattering, we have determined that short-range antiferromagnetic correlations develop at low temperatures. Applied magnetic fields induce a magnetic transition, in which the short-range order abruptly expands into a long-range order. | eng_Latn | 27,914 |
Theoretical investigation of topological ferrimagnetic intertwining double chain | In this paper, a novel trimeric chain approach to organometallic ferrimagnetics is proposed. The inter and intratrimer exchange interaction has been determined to be antiferromagnetic from a theoretical model magnetic susceptibility. The Curie law observed at very low temperature ( q = 5.764 K l0) contrasts with significant ferromagnetic behaviour. The magnetic data were fitted with the IDC model. The compounds interestingly exhibit ferrimagnetic interactions with g Cu1 =1.81, g Cu2 =2.04 and g Cu3 =2.43; J 1 =-89.93K and J 2 = -2.68 K | This contribution is concerned with the occurrence of metallic character in K-doped systems and the non-occurrence in Na-doped systems. An N-fold degenerate Hubbard model in the Gutzwiller approximation, previously presented by Jian Ping Lu, is utilized to discuss the metal–insulator transitions observed in these alkali-doped fullerides. The parameters used are derived from INDO calculations in the molecular cluster approach. © 1995 John Wiley & Sons, Inc. | eng_Latn | 27,915 |
Vortex imaging in magnesium diboride with H ⊥ c | We have performed scanning tunneling spectroscopy imaging of vortices in ${\mathrm{MgB}}_{2}$ with both the tunneling current and the applied field perpendicular to the crystalline c axis. This revealed a well ordered vortex lattice with a relatively low anisotropy of $1.19\ifmmode\pm\else\textpm\fi{}0.04.$ This is significantly below the upper-critical-field anisotropy, but in good agreement with theoretical predictions for the penetration depth anisotropy, which at low fields is expected to be dominated by the $\ensuremath{\pi}$ band. The value of the anisotropy is smaller than estimated from small-angle neutron-scattering measurement. | Abstract An exact, three-dimensional, analytical description of the current distribution in the nozzle of an MHD channel, under imposed open conditions, is obtained. Strong vorticity of the current flow and high current concentration in the small regions toward the one side of the sidewalls and near the exit of the channel are found. | eng_Latn | 27,916 |
Methicillin-resistant and -susceptible Staphylococcus aureus sequence type 398 in pigs and humans. | Methicillin-resistant Staphylococcus aureus sequence type 398 (ST398 MRSA) was identified in Dutch pigs and pig farmers. ST398 methicillin-susceptible S. aureus circulates among humans at low frequency (0.2%) but was isolated in 3 human cases of bacteremia (2.1%; p = 0.026). Although its natural host is probably porcine, ST398 MRSA likely causes infections in humans. | A model Hamiltonian representing the Cu spins in La2CuO4 in its low-temperature body-centred orthorhombic phase, that includes both spin–orbit-generated Dzyaloshinskii–Moriya interactions and interplanar exchange, is examined within the RPA utilizing a Tyablikov decoupling of various high-order Green's functions. The magnetic susceptibility is evaluated as a function of temperature and the parameters quantifying these interactions, and compared to recently obtained experimental data of Lavrov, Ando, and collaborators. An effective Hamiltonian corresponding to a simple tetragonal structure is shown to reproduce both the magnon spectra and the susceptibility of the more complicated body-centred orthorhombic model. | eng_Latn | 27,917 |
Half-metallic properties and stability of ferromagnetic state in the full-heusler alloys (FexRu1-x)2CrSi (0 ≤ x ≤ 1) | We investigate the half-metallic properties and the stability of the ferromagnetic state in the alloys (Fe x Ru 1-x ) 2 CrSi (0 ≤ x ≤ 1) with orderly and disorderly atomic arrangement based on the Heusler structure. It is predicted from the electronic structures that the ordered alloys are half-metals in the range of 1/3 < x < 3/4 and ferromagnets with high spin polarization in the range of 3/4 ≤ x ≤ 1. However in the ferromagnetic state, the atomic arrangement with the Fe-Cr disorder tends to be energetically more favorable than the orderly arrangement, and the Fe-Cr disorder decreases the spin polarization of the ordered alloys. This is attributed to the fact that occupation of Cr sites by Fe destroys the gap near the Fermi energy in the minority spin state. But, because the Fe-Cr disorder shows a tendency to keep the spin polarization high as x increases, it is deduced that (Fe x Ru 1-x ) 2 CrSi are materials with high spin polarization if x is high. | The hyperfine coupling constants and the natural radiative lifetimes of the 5 p 2 P 3/2 and 6 p 2 P 3/2 levels of K 39 were determined in a level crossing experiment on an enriched K 39 sample in a sealed-off resonance cell. The following results were obtained: ----- -- a (5 p 2 P 3/2 ) = 1.973 (12) MHz -- a (6 p 2 P 3/2 ) = 0.886 (8) MHz ----- -- b (5 p 2 P 3/2 ) = 0.870 (18) MHz -- b (6 p 2 P 3/2 ) = 0.370 (15) MHz ----- -- I(5 p 2 P 3/2 ) = 133 (3) ns -- I(6 p 2 P 3/2 ) = 310 (15) ns ----- Considering the influence of core polarization on the magnetic hyperfine interaction and applying a Sternheimer correction, fairly consistent values of the electric quadrupole moment Q are obtained from the first three levels of the np 2 P 3/2 sequence. We find Q (K 39 ) = +0.059 (6) barn. | eng_Latn | 27,918 |
STUDY OF THE MAGNETIC PROPERTIES OF THE YTTRIUMYTTERBIUM GARNET SYSTEM | The yttrium-ytterbium (Y-Yb) garnet system Y3-xYbxFe2O12 was investigated at the compositions for which x=0, 0.75, 1.50, 2.25 and 3.00. The samples were prepared by the co-precipitation method and sintered 7 hours in oxygen atmosphere at 1350℃ or 1400℃. Lattice constants and theoretical densities were determined from X-ray diffraction data. It was found that the whole system consisted of a single phase with the garnet structure, and the lattice constant decreased linearly from 12.371 A (Y3Fe5O12) to 12.297 A (Yb3Fe5O12). The static hysteresis loop, the initial permeability at 500 Kc, the saturation magnetization between liquid-air temperature to the Curie point and the magnetic spectrum between 500 Mc and 3000 Mc were observed as a function of compositions. It was found that all the samples had high bulk densities ( 90 % theoretical densities) and high resistivities (109-1010 ohm-cm), and that the saturation magnetization Vs temperature curves had positive slopes at 10W temperature for x ≥ 1.50. | This Letter describes a calculation using superfield techniques, showing that the ..beta.. function is zero to three loops in N=4 supersymmetric Yang-Mills theory. This result gives further indication that the theory is likely to be finite and conformally invariant order by order in perturbation theory. | yue_Hant | 27,919 |
Superconducting Proximity Effects in Magnetic Metals | We explain the basic physics behind oscillatory effects in superconductor/metallic ferromagnet (S/F) sandwiches, and describe the important effects of the spin orbit scattering in these systems. We find that spin-orbit scattering plays a major role in the physics of the superconducting proximity effect with a conducting ferromagnet. As examples, we present calculations of the T{sub c} of an S/F bilayer and the Josephson current (near T{sub c}) of an S/F/S trilayer. {copyright} {ital 1997} {ital The American Physical Society} | Abstract The band structures and partial density of states of MM ′ X half-Heusler compounds as topological insulators have been simulated by using local density approximate + U . Results show that both the covalent M ′ –X bonds and the ionic M–M ′ bands contribute the band structures, and the covalent bonds between M ′ and X atoms decide the number of ( E Γ6 − E Γ8 ) (Γ 6 and Γ 8 denote the twofold s -type orbitals and fourfold p -type orbitals and M , M ′, and X show atoms located at different positions in the lattice); big size of | χ M ′ − χ X | and small value of V are propitious to form topological insulators. | eng_Latn | 27,920 |
Structure nucleaire de BaCaFe4O8 | Resume We describe the preparation and crystallographic properties of a new ferrite: BaCaFe 4 O 8 . The c ompound crystallizes in the trigonal space group P31m, with the following lattice parameters: a=5,407±0,001A b=7,703±0,003A | Conception d'un simulateur de propulsion pour etudier les performances d'une helice contrarotative | fra_Latn | 27,921 |
Fully Gapped s-wave-like Superconducting State and Electronic Structures in the Ir0.95Pd0.05Te2 Single Crystals with Strong Spin-orbital Coupling | Due to the large spin-orbital coupling in the layered 5d-transition metal chalcogenides compound, the occurrence of superconductivity in Ir2-xPdxTe2 offers a good chance to search for possible topological superconducting states in this system. We did comprehensive studies on the superconducting properties and electronic structures of single crystalline Ir0.95Pd0.05Te2 samples. The superconducting gap size, critical fields and coherence length along different directions were experimentally determined. Macroscopic bulk measurements and microscopic low temperature scanning tunneling spectroscopy results suggest that Ir0.95Pd0.05Te2 possesses a BCS-like s-wave state. No sign of zero bias conductance peak were found in the vortex core at 0.4K. | Abstract A layer of random defects in the simple cubic Ising model with nearest neighbor ferromagnetic interactions of strength J is considered. Using the real space renormalization group method we calculate defect free energy in the whole temperature range. Specifically, we analyze: the layer of diluted defects, the layer of spin-glass type defects, and the layer of mixed defects. The free energy is strongly dependent on the value of couplings between the defect and the bulk. | eng_Latn | 27,922 |
Anomalous spin‐wave excitations in a one‐dimensional Dzyaloshinski–Moriya antiferromagnet | The dynamics of a one‐dimensional Heisenberg antiferromagnet with a small Dzyaloshinski–Moriya component to the exchange interaction is considered. The spin rotational invariance within the easy plane is broken by the application of a weak magnetic field in the easy plane. The nature of the spin‐wave excitations of the quantum spin system is investigated, and pronounced anomalies in the single‐spin‐wave spectrum at fields comparable to the anisotropy in the exchange interaction are found. These anomalies are of quantum character and are related to the resonance between the single‐spin‐wave and the two‐spin‐wave excitations. The implications for the two‐spin‐wave bound states are discussed. | Abstract : Theoretical calculations on the trajectory of an electron beam of kilovolt energy range in an ionospheric environment have been performed. By means of a succession of orthogonal transformations, the trajectory and luminosity as observed at a photometer with a given angular field of view are obtained. For the purpose of applications on rocket beam experiments, cases of various magnetic field orientations and beam energies have been examined. Singularities of luminosity exist in this model when the magnetic field is perpendicular to the electron velocity resulting in a non-propagation mode. (Author) | eng_Latn | 27,923 |
Microstructure and magnetic properties in Mn-doped Nd-Fe-B magnets | Abstract The effect of the addition of antiferromagnetic element Mn on the local structure and the magnetic properties of Nd 9 Fe 85 B 6 magnets has been studied. It was found that the microstructure and local structure heavily depended on both the Mn addition and the quenched speed. The Mn additions could promote the order degree around Fe atom in as-spun samples. After appropriate annealing, the completely crystallized samples were obtained. It showed that the difference of the local structures around Fe atoms almost disappeared and the hard magnetic properties, especially the coercivity was enhanced. It is presumed that the enhanced hard magnetic properties were attributed to the enhancement of the exchange coupling, which is between the hard phases and the soft phases. | The structure of a crystal of composition FeB/sub approximately 49/ has been investigated using single-crystal diffractometry. The space group is R3m and the hexagonal cell dimensions are a = 10.951 A and c = 23.861 A. The three-dimensional boron network is essentially equivalent to that found in ..beta..-rhombohedral boron. Two sets of holes in this network are partially occupied by iron atoms. | eng_Latn | 27,924 |
Structural, mechanical and electronic properties of OsTM and TMOs2 (TM = Ti, Zr and Hf): First-principles calculations | Abstract The first-principles calculations have been performed to study the structural, elastic, mechanical and electronic properties of cubic OsTM (TM = Ti, Zr, and Hf) and hexagonal TMOs 2 compounds. The calculated structural parameters are in good agreement with the available experimental data. To the best of our knowledge, the elastic constants of OsTM and TMOs 2 compounds have been obtained for the first time. The calculated elastic and mechanical properties show that these compounds have no superhard character. These compounds are mechanically stable and behave in ductile manner. The electronic band structures and densities of states of OsTM and TMOs 2 compounds have been analysed. OsTM has a mixture of covalent-ionic and metallic character, and TMOs 2 has strong metallic nature. | On the basis of Lee-Low-Pines unitary transformation, the influences of Rashba spin–orbit (RSO) coupling energy and Zeeman splitting energy on the ground-state energy of polaron in a quantum rod (QRD) have been studied by using a variational method of Pekar type. Taking the RSO interaction and the Zeeman splitting into account, we derive the variational relations of the absolute ratios \( \zeta_{1} \) and \( \zeta_{2} \) of the RSO coupling energy and the Zeeman splitting energy to the ground-state energy of polaron with the transverse confinement radius (TCR) and the longitudinal confinement length (LCL) of QRD, as well as and the magnetic field adjusting length (MFAL). The results show that the absolute ratios \( \zeta_{1} \) and \( \zeta_{2} \) will increase when the TCR and the LCL become larger, but will slowly decrease while the MFAL and the aspect ratio of the ellipsoid \( \delta \) increase, respectively. The above results can be attributed to the spin effects and interesting quantum size confining. | eng_Latn | 27,925 |
A gold-197 Mössbauer investigation of various gold(I) derivatives of five- or six-membered nitrogen-containing heterocycles | The Mossbauer spectra of (triphenylphosphine)AuQ (QH is an imidazole, 2-pyridone, or theobromine), of 2-phenylimidazolylgold(I), and of 1-phenyl-3-methyl-4,4′-bis(triphenylphosphinegold)pyrazolone-5 are reported and discussed. Comparison with the available data, including X-ray crystal structures, shows that 197Au spectroscopy is helpful in the assignment of the coordination environment around the gold atom in the solid state even in the absence of crystals suitable for X-ray studies. | A family of one-dimensional magnetic Hamiltonians is introduced, where at each site there are $n$ spin-$S$ operators. It is shown that, for special couplings between spins and for $S=\frac{1}{2}$, the model contains the complete spectrum of the Heisenberg chain with spins \textonehalf{}, 1, frac32;, etc., and the ground state is that of the corresponding Heisenberg chain. By the varying of a single parameter the model allows continuous transitions between chains with different spin. We map the spin-($S+S$) model onto the nonlinear $\ensuremath{\sigma}$ model and discuss the possibility of a finite gap in the spin-(\textonehalf{}+\textonehalf{}) model. | eng_Latn | 27,926 |
Vortices with Ferromagnetic Superfluid Core inHe3-B | It is shown that there may exist five axisymmetric vortices in $^{3}\mathrm{He}$-$B$, different in their internal symmetries. The Landau theory for phase transitions between them is constructed. Numerical calculations show that one of the observed vortices possesses a novel new structure: a superfluid core, which is ferromagnetic. This explains the measured large magnetic moment of the vortex. | We studied the dynamics of isolated vesicles as well as vesicle interactions in semi-dilute vesicle suspensions subjected to a shear flow. We found that the long-range hydrodynamic interactions between vesicles give rise to strong fluctuations of vesicle shape and inclination angle, , though the functional dependence of and the transition path to tumbling motion is preserved. The dependence of the suspension viscosity on the viscosity ratio between inner and outer fluids, ?, was found to be non-monotonic and surprisingly growing with ? at the fixed outer fluid viscosity for ?<1, at odds with recent predictions made for a dilute suspension of non-interacting vesicles. | eng_Latn | 27,927 |
High-energy spin dynamics in La1.69Sr0.31NiO4. | To test the prediction that the dispersion of the magnetic resonance in superconducting YBa 2 CU 3 O 6 + x is similar to magnons in an incommensurate antiferromagnet, we have mapped out the spin dynamics in a stripe-orderednickelate, La 2 - x Sr x NiO 4 , with x≃0.31, using inelastic neutron scattering. We observe spin-wave excitations up to 80 meVemerging from the incommensurate magnetic peaks with a surprisingly large and almost isotropic spin velocity: hcs, ∼ 0.32 eV A. A comparison indicates that the inferred spin-excitation spectrum is not, by itself, an adequate model for the magnetic resonance feature of the superconductor. | Ab initio calculations were performed on Si_(60)(I_(h)) and its several lower symmetrical structures.Five stable structures of spherical Si_(60) with T,C_(i),C_(1),C_(s) and C_(2) symmetries were found by following the imaginary frequency vibrations of Si_(60)(I_(h)),Si_(60)(D_(3d)) and Si_(60)(T_(h)).The calculated results demonstrate that some silicon atoms pop out and some shrink inward in the five favored structures of Si_(60),leading to form sp~(3) hybridization of silicon.These results will provide insight into the formation and stability of nanoscale silicon clusters. | eng_Latn | 27,928 |
The Stark resonances near zero energy | Simple formulae for the energies and widths of the Stark levels in the neighbourhood of the zero-field ionization threshold are deduced. Comparison with the results of exact numerical calculation shows that the formulae obtained are of high accuracy for both the negative and positive energy regions. | Abstract The spin-phonon spin 1 2 Heisenberg system is found to have the same critical index for the susceptibility as the ideal, rigid lattice ferromagnet. This is in accordance with the criterion for critical index renormalisation expounded by Fisher in terms of the sign of the specific heat index. | eng_Latn | 27,929 |
Network service control point (SCP) for an intelligent network | SCP so far not exclusive owner of the cooperation existing business applications and network SCP. Resolve this issue by the present invention. | This work benchmarks density functional theory, with several different exchange-correlation functionals, for prediction of isotropic one-bond phosphorus-hydrogen NMR spin-spin coupling constants (SSCCs). Our test set consists of experimental SSCCs from 30 diverse molecules representing multiple phosphorus bonding environments. The results suggest the importance of a balance between the choice of correlation functional and the admixture of nonlocal exchange. Overall, standard DFT methods appear to suffice for usefully accurate predictions of (31)P-(1)H SSCCs. | eng_Latn | 27,930 |
High coercivity of melt–spun Sm2Fe15Al2C1.5 compound | The magnetic hardening of melt–spun Sm2Fe17Cx was studied and the coercivity of 4.6 kOe for Sm2Fe17C1.5 alloys was reported a few years ago. Recently, we have succeeded in preparing single‐phase compounds of Sm2(Fe, M)17Cx (M=Ga, Al, or Si) with high carbon concentration by arc melting. It was found that the substitution of Ga or Al not only facilitated the formation of high carbon concentration rare‐earth iron compounds with a 2:17‐type structure, but also was very effective in raising the value of the anisotropy field. For example, the sample of Sm2Fe15Al2C1.5 has a saturation magnetization of 110.2 emu/g, a Curie temperature of 576 K, and an anisotropy field of 111 kOe. It is known that melt spinning is an effective means to obtain high coercivity of magnetically hard materials. In this work, the hard magnetic properties of melt–spun Sm2Fe15Al2C1.5 alloys were investigated. It was found that the value of coercivity depends strongly on the quenching rates and an optimum coercivity of 9.4 kOe was obtaine... | Abstract Electronic structure calculations of MS10−6 clusters (M = Mn, Fe, Co, Ni) have been performed making use of the Xα discrete variational method. The results of the calculations are used for the detailed interpretation of the X-ray emission and photoelectron spectra for Mn, Fe, Co and Ni monosulphides and in a discussion of the physical-chemical properties of the compounds under investigation. | eng_Latn | 27,931 |
Thermal magnetization rotation of small nanoparticles | In this paper, thermal magnetization rotation of small Co nanoparticles was investigated. We test the performance and validity of a semi-implicit time integration scheme. | The macroscopic description of the collective motion of a highly excited nucleus is found through statistical averaging over many microscopic states of the quantum system. The relation connecting the quantities characteristic of macroscopic models (the multipole orders of the spatial oscillations of the density, the frequencies of the natural oscillations) and the quantum quantities specified by the conditions of the quantum experiment (the angular momentum and the energy transferred to the nucleus) is investigated. | eng_Latn | 27,932 |
Generation–Collection Electrochemistry Inside a Rotating Droplet | In this work, we explore generation–collection electrochemistry in a rotating droplet hydrodynamic system, where a 70 μL droplet containing a redox active species (ferrocyanide) is sandwiched between an upper rotating rod and bottom nonmoving generator and collector planar electrodes. In such a system, we studied the effect of the counter electrode reaction on the recorded generator current, and the effect of the generator–collector distance (ranging from 3 to ca. 500 μm) on the collection efficiencies obtained at rotation rates ranging from 50 to 1100 rpm. We found that the counter electrode reaction competes with the collector reaction for the regeneration of the electroactive species; thus, collection efficiencies of 100% are probably impossible to obtain with this system geometry. We found that the collection efficiency increases with the droplet rotation rate and decreases with the generator–collector distance. The highest collection efficiency we obtained is 62% for the generator–collector distance ... | Preface 1. Cellular disorder 2. Topographical disorder 3. Continuum disorder 4. The observation of disorder 5. Statistical mechanics of substitutional disorder 6. Thermodynamics of topological disorder 7. Macromolecular disorder 8. Excitations on a disordered linear chain 9. Excitations on a disordered lattice 10. Electrons in disordered metals 11. Excitations of a toplogically disordered network 12. Dilute and amorphous magnets 13. Electrons in 'gases' References Index. | eng_Latn | 27,933 |
Neutron diffraction studies of lattice parameters and the phase diagram of K1−x (NH4) x SCN solid solutions | Results of temperature and concentration dependence investigations of unit cell parameters and volume of K1−x (NH4) x SCN mixed crystals by powder neutron diffraction are presented. It is shown that the transformation from monoclinic phase III to orthorhombic phase II starts at low temperatures nearx=0.75. | Abstract A procedure is given for calculating the NMR lineshape of a cluster of spins imbedded in a molecule which is rotating with free or restricted motion. It is shown that for the isotropic diffusion model (assuming a correlation time τ c such that 1/ τ c ⪢ H DD / lstrok ; h where H DD is the dipole interaction) the line shape is Lorentzian as expected and has a width equal to that obtained from a standard T 2 calculation using the appropriate autocorrelation function. For τ c which do not satisfy this condition the lineshape is no longer Lorentzian, and an example for this condition is shown. The usefulness of the procedure lies in obtaining lineshapes for systems whose motion is too complex for an autocorrelation function to be obtained unambiguously. | eng_Latn | 27,934 |
Pt and Co3O4 supported on ceria and zirconia for the catalytic reduction of N2O in the presence of CO | Abstract Ceria (CeO2) and zirconia (ZrO2) supported Pt and Co3O4-based nanocatalysts were synthesized and characterized by different instrumental techniques. The catalysts redox properties and active surface areas were evaluated using temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO) and H2-pulse chemisorption, respectively. The catalysts were tested for the thermal oxidation of carbon monoxide (CO), reduction of nitrous oxide (N2O) and conversion of N2O/CO mixture (1:1 vol%) . In catalytic tests, Pt–Co3O4/CeO2 (10:10%) oxidized CO up to 100% at 25 °C and Co3O4/CeO2 (20%) reduced N2O up to 90% at 320 °C. Moreover, Pt–Co3O4/CeO2 (10:10%) converted N2O/CO mixture to N2/CO2 up to 90% at about 210 °C. The low-temperature catalytic activity of Pt–Co3O4/CeO2 (10:10%) for CO oxidation and N2O/CO mixture redox conversion were attributed to uniform particle size, metals and support proper combination and electron interaction. | Based on density functional calculations, we present a detailed theoretical study of the electronic structure and the magnetic properties of the quasi-one dimensional chain cuprate Li_2ZrCuO_4 (Li_2CuZrO_4). For the relevant ratio of the next-nearest neighbor exchange J_2 to the nearest neighbor exchange J_1 we find alpha = -J_2/J_1 = 0.22\pm0.02 which is very close to the critical point at 1/4. Owing this vicinity to a ferromagnetic-helical critical point, we study in detail the influence of structural peculiarities such as the reported Li disorder and the non-planar chain geometry on the magnetic interactions combining the results of LDA based tight-binding models with LDA+U derived exchange parameters. Our investigation is complemented by an exact diagonalization study of a multi-band Hubbard model for finite clusters predicting a strong temperature dependence of the optical conductivity for Li_2ZrCuO_4. | eng_Latn | 27,935 |
Extraction of R-Phycoerythrin from Kappaphycus alvarezii (Doty) Doty ex Silva and analyses of its physico-chemical properties | The phycoerythrin (PE) is a protein acting as a photosynthetic accessory pigment in red algae (Rhodophyta). This protein has gained many biotechnological applications in food science, cosmetics and analytical processes. In this study, phycoerythrin of red macro alga Kappaphycus alvarezii was extracted by freezing and thawing method in sodium phosphate buffer (0.1 M). The protein was precipitated with 60% ammonium sulphate saturation and dialysed against the same buffer (10 mM) and lyophilized. The R-PE was analysed for its various physico-chemical properties and the analyses revealed that R-PE has characteristic affinity towards different metal ions, inhibitors, organic solvents, preservatives at different monochromatic irradiances. | The magnetization M under temperature 1.72K in the range of magnetic field B 0‐5T and the magnetic susceptibility (MS) under magnetic field 0.1T in the temperature range 1.7 400K of the powder and crystal PbTe:Eu samples fabricated from the bulk and surface layers of the doped ingots grown from the melt by the Bridgman method are investigated. Specific magnetic properties in the Eu-doped PbTe single crystals are revealed: (i) the strong dierences between the magnetization and MS of the surface and bulk of the PbTe:Eu doped ingots; (ii) strong paramagnetism of the surface layers practically independent of T in the temperature range over 30K; (iii) the principal discrepancies between the temperature dependences of MS of the crystal matrix of powder and crystal doped samples. Possible mechanisms of the appearance of the mentioned peculiarities of the magnetic properties of dierent | eng_Latn | 27,936 |
Uncompensated Antiferromagnetic Ordering of UAu$_2$Si$_2$ Studied by $^{29}$Si-NMR | The magnetically ordered phase of body-centered tetragonal UAu$_2$Si$_2$ was explored through $^{29}$Si-NMR experiments. The field-swept NMR spectra show asymmetric peak splitting below magnetic phase transition temperature, $T_{\rm m}$ = 20 K. This splitting is well explained by the occurrence of a magnetic order with propagation vector of $q$ = (2/3, 0, 0) and magnetic moments pointing parallel to the tetragonal [001] axis, offering evidence for uncompensated"up-up-down"-type antiferromagnetic ordering with a spontaneous [001] magnetization component. A symmetry analysis of the hyperfine-coupling tensor with phenomenological corrections including orbital and dipolar-field contributions yields the magnitude of the ordered moment to be approximately 1.4 $\pm$ 0.2 Bohr magneton per uranium ion, and evaluates the site-dependent hyperfine-coupling constants. | For pt.I see ibid., vol.5, no.7, p.1307 (1975). A theory is developed to describe the Fermi surface changes in dilute alloys. Following the arguments of Stern, the Fermi energy is considered to be unchanged by alloying and the anisotropic energy shift of the bands is given by the forward part of the T matrix which is then calculated using a muffin tin approximation to describe the alloy. Partial wave analysis gives the Fermi surface changes in terms of anisotropy function and a set of scattering parameters which are conveniently expressed as 'Friedel phase shifts' and which can be determined by fitting the anisotropy of the experimental results. It is shown that the model is closely related to the average T matrix approximation. The observed changes of Fermi surface volume in Cu(Al) and Cu(Ni) alloys are successfully explained and the Friedel sum is also obtained correctly. | eng_Latn | 27,937 |
SPECIFIC MAGNETIC PROPERTIES OF THE Eu-DOPED PbTe SINGLE CRYSTALS | The magnetization M under temperature 1.72K in the range of magnetic field B 0‐5T and the magnetic susceptibility (MS) under magnetic field 0.1T in the temperature range 1.7 400K of the powder and crystal PbTe:Eu samples fabricated from the bulk and surface layers of the doped ingots grown from the melt by the Bridgman method are investigated. Specific magnetic properties in the Eu-doped PbTe single crystals are revealed: (i) the strong dierences between the magnetization and MS of the surface and bulk of the PbTe:Eu doped ingots; (ii) strong paramagnetism of the surface layers practically independent of T in the temperature range over 30K; (iii) the principal discrepancies between the temperature dependences of MS of the crystal matrix of powder and crystal doped samples. Possible mechanisms of the appearance of the mentioned peculiarities of the magnetic properties of dierent | The method of electron paramagnetic resonance has been used to determine the localization of Mn2+ ions in X and A zeolites partially exchanged for Mg2+ and Ca. ::: ::: ::: ::: The EPR spectra of Mn2+ ions recorded in X and Q bands in parallel have been interpreted based on computer simulation of EPR powder spectra of paramagnetic ions with electron and nuclear spins S = J = 5/3. The spectra have been divided into 7 types corresponding to various localizations of Mn2+ ions in the zeolites studied. | yue_Hant | 27,938 |
Nonlinear magnetization of niobium near Hc2 | Abstract In a previous paper we reported the measurements of both C/T and đ Q /d H of high-purity niobium as functions of the applied field at a number of chosen temperatures. In the present paper we analyze the slopes of these “magnetocaloric” quantities in the reversible region near H c2 . These slopes are related to the nonlinearity of the magnetization curve by means of a third-order field term in the Gibbs free energy. At the chosen temperatures the small values of the coefficient of this field term are calculated and found to be in agreement with the model of the reversible magnetization curve proposed by Kes. | The aim of this paper is to discuss the possibility of theoretically engineering multifunctional nanomaterials. The calculations were performed for 1D and 2D nanomaterials by using results obtained within the Hubbard model (HM). The main results of the HM are briefly reviewed. The conclusion is that the approach taken in this paper is a distinct improvement over those in the literature.In the present paper results of applications of the HM are directly used in examples of engineering nanomaterials. On the other hand, in the literature calculations were performed by ab initio methods and then fitted to the form of the Hamiltonian of the HM. | eng_Latn | 27,939 |
An average-magnetization analysis of R 1ρ relaxation outside of the fast exchange limit | Approximate expressions for the NMR spin relaxation rate constant in the rotating frame of reference R 1ρ are derived for two-site chemical exchange by consideration of the evolution of the average density operator using the stochastic Liouville equation. R 1ρ is obtained as a linearized approximation to the largest (least negative) eigenvalue of the matrix describing the evolution of the average density operator in the long-term limit. The expressions obtained are more accurate than existing expressions when exchange is not fast and the populations of the exchanging sites are close to equal. The new expressions for R 1ρ facilitate the interpretation of chemical exchange phenomena in proteins and other biological macromolecules. | We consider the throughput performance of ARQ in interfering channels, where the signal of interest as well as the interferers are subject to independent distributed Nakagami-m block fading. The key contribution is the derivation of closedform expressions for the rate-maximized throughput. For this purpose, we employ the powerful parameterization approach from [1], allowing the problem to be solved exactly in a closedform. We also consider the scaled-power, and the interferencelimited, case. | eng_Latn | 27,940 |
Direct observation of ferrimagnetic/ferroelastic domain interactions in magnetite below the Verwey transition | Abstract The magnetic behaviour of magnetite at low temperatures is dominated by its transformation to a monoclinic crystal structure that is simultaneously ferrimagnetic, ferroelastic and ferroelectric below ∼ 125 K (the Verwey transition). Here we use electron microscopy to reveal the relationship between ferrimagnetic and ferroelastic domain structures in monoclinic magnetite. We present dynamic observations of magnetite during heating and cooling across the Verwey transition, revealing a diversity of unexpected interaction phenomena between crystallographic twins and magnetic domain walls. This study provides a new understanding of the low-temperature magnetic properties of magnetite that will affect a broad range of rock magnetic studies, from the interpretation of magnetic remanence in terrestrial rocks and sediments to the search for biogenic magnetite in extraterrestrial materials. | We present an electronic structure calculation of the valence band for some II--VI binary/ternary alloy interfaces. We use the empirical tight-binding method and the surface Green's function matching method. For the ternary alloys we use our previously set Hamiltonians they describe well the band gap change with composition obtained experimentally. At the interface domain, we find three non-dispersive and two interface states besides the known bulk bands. The non-dispersive states are reminiscent of the ones already obtained experimentally as well as theoretically, in (001)-oriented surfaces. We make use of the available theoretical calculations for the (001)-oriented surfaces of the binary compounds and for the binary/binary interfaces to compare our new results with. | eng_Latn | 27,941 |
Oxidative decomposition of chloropentafluoroethane (CFC-115) in the presence of butane over metal oxides supported on alumina-zirconia | The catalytic oxidative decomposition of chloropentafluoroethane (CFC-115) was carried out in the presence of butane with various metal oxides supported on alumina-zirconia. Tungsten(VI) oxide alone had a positive effect on the activity among all the metal oxides. It was concluded that the active sites of the tungsten(VI) oxide catalyst supported on alumina-zirconia might be the acid sites formed by the interaction between tungsten(VI) oxide and tetragonal zirconia. This catalyst was found to be the most active of all the catalysts which have so far been examined, and kept a high activity during the oxidative decomposition of CFC-115 for 25 h. | Abstract We report an in-depth investigation of the critical behavior in Ni0.15Cu0.15Zn0.7Fe2O4 (NCZFO) spinel ferrite synthesized via the solid-state reaction method. The structural analysis demonstrates that NCZFO belongs to the Fd 3 ¯ m space group of the cubic crystal system. The magnetic transformation in NCZFO at approximately TC = 290 K is of the second order, as per the Banerjee criteria. Employing various models, we have attempted to estimate the CP (critical parameter) values. The self-consistency of the CPs is confirmed by Widom's relation as well as the scaling hypothesis. The values of the CPs manifest that the magnetic ordering in NCZFO belongs to the Heisenberg theory in three dimensions, signifying short-range ferromagnetic interactions. The relationship between the exchange distance (J(r)) and the spatial distance (r) in NCZFO are expected to decline as J(r) ∼r−4.947. | eng_Latn | 27,942 |
Teleportation via thermally entangled state of a two-qubit Heisenberg XXX chain | Abstract In this paper, we consider the 1D two-qubit isotropic antiferromagnetic Heisenberg XXX model in an external magnetic field B. Firstly, we pay our attention to study the properties of thermal entanglement in XXX model, and in comparison with XX model, we found that the thermal entanglement could be easily obtained and quantum phase transition could not easily occur in XXX model. Finally, we calculate the fidelity of teleportation of one-qubit pure state via thermally entangled state of a two-qubit Heisenberg XXX chain, in the same way, we compare XXX model with XX model, we found that teleportation via thermally entangled state of a two-qubit Heisenberg XXX chain may be better. | This paper is aimed at dissecting and discussing the effect of high pressure on chirogenesis, thus unveiling the role of this universal force in astrochemical and primeval Darwinian scenarios. The first part of this contribution revisits the current status and recent experiments, most dealing with crystalline racemates, for which generation of metastable conglomeratic phases would eventually afford spontaneous resolution and hence enantioenriched mixtures. We then provide an in-depth thermodynamic analysis, based on previous studies of non-electrolyte solutions and dense mixtures accounting for the existence of positive excess volume upon mixing, to simulate the mirror symmetry breaking, the evolution of entropy production and dissipation due to enantiomer conversion. Results clearly suggest that mirror symmetry breaking under high pressure may be a genuine phenomenon and that enantioenrichment from initial scalemic mixtures may also take place. | eng_Latn | 27,943 |
17O Quadrupole Dips in Ammonium Persulphate | zThe magnetic field dependence of the 1 H spin-lattice relaxation time in ammonium persulphate shows pronounced minima near the 1 H magnetic resonance frequencies of 1,200 and 2,200 kHz. These are interpreted in terms of a model involving cross-relaxation between 1 H in the NH 4 + ion and 17 O in natural abundance in the S 2 O 8 2− ions, the latter having a much shorter spin-lattice relaxation time. A theoretical analysis of the shape of the minima is used to derive values for the 17 O quadrupole parameters. This analysis results in best estimate values for the quadrupole coupling constant of 6.75 (± 0.05) MHz and an asymmetry of 0.30 (± 0.02). Such values are indicative of 0 − H hydrogen bonding and suggest the S 2 O 8 2− ion is not undergoing rapid reorientation at temperatures below 320 K | Abstract : Discussed is a preparative method for preparing antioxidant, anticorrosive and detergent additives to petroleum products. The additives are alkyl derivatives of bis((imidazolyl)CH2CH2NHS-). The additives are prepared by reacting monocyclic disubstituted imidazolines with sulfur chloride at 40-70 degrees centigrade in benzene solution. | eng_Latn | 27,944 |
Special interference fringes in Michelson interferometer experiment | The expression of the optical path is educed when the spectroscope in Michelson interferometer is reversed. The reason of the appearance of elliptic or hyperbolic interference fringes is explained. | We propose a setup which allows us to couple the electron spin degree of freedom to the mechanical motions of a nanomechanical system not involving any of the ferromagnetic components. The proposed method employs the strain-induced spin-orbit interaction of electrons in narrow gap semiconductors. We have shown how this method can be used for detection and manipulation of the spin flow through a suspended rod in a nanomechanical device. | eng_Latn | 27,945 |
First-principles calculations of the spin-orbit scattering cross section of sp impurities in Mg. | The spin-orbit scattering of 4sp and 5sp impurities in a Mg host is investigated theoretically by self-consistent local-density-functional theory. The calculated spin-orbit scattering cross sections σ SO agree with the available experimental results for low valent impurities. For higher valent impurities we predict a p resonance behavior. For Cu and Ag impurities our results point to errors of density-functional theory in estimating the d contribution to σ SO . In total a consistent interpretation of the trends is given | By feeding the silkworms with the nano Fe3O4 powder together with mulberry leaves, we directly obtained silkworm spun pristine magnetic silk fiber, MSF. To compare with the normal SF found that this MSF not only has expected magnetic properties, but also has enhanced thermal stability and mechanical properties, e.g. stress and strain. | eng_Latn | 27,946 |
Alternant Molecular Orbitals without Spin Projections | A new method for utilizing different orbitals for different spins is proposed which obviates the procedures usually employed to project states of desired multiplicities out of a single determinantal function. The method, which calculates an approximation to a spatial eigenfunction of the Hamiltonian rather than to the total wavefunction itself, serves to simplify calculations not only for alternant molecular orbitals, but also for wavefunctions of the valence‐bond and nonpaired spatial‐orbital type. | ABSTRACTThis letter is motivated by an apparent paradox, in that some quaternary systems (particularly in the Ti–Zr–Al–C system) have been shown to exhibit M-site out-of-plane ordering, while prior work and calculations by the present authors suggest endothermic interactions between Zr and Ti. In this letter we provide a resolution to this issue and provide a more extended analysis on the out-of-plane and in-plane ordering in the M sites of quaternary MAX alloys. The results provide further insights to develop criteria to predict potential out-of-plane ordering tendencies in other MAX systems.fx1 | eng_Latn | 27,947 |
Modified synthesis of nanoscale zero-valent iron and its ultrasound-assisted reactivity study on a reactive dye and textile industry effluents | AbstractSynthesized nanoscale zero-valent iron (NZVI) particles were applied for the degradation of a reactive dye Remazol Black B 133 and textile effluent. XRD and HR-TEM analysis of the synthesized particles showed body centered cubic crystal packing. The aggregates were spherical in shape and the size of the particles ranged from 5 to 15 nm. The reactive dye solution was substantially degraded by NZVI particles using ultrasonic irradiation under various experimental conditions created by varying NZVI dosages (0.15–0.30 g/L), initial dye concentration (25–200 mg/L), and pH (2–13). Experimental results suggest that NZVI particles work best within the pH range of 4–10. A unit gram of NZVI was found to degrade a maximum of 749.2 mg of RB B 133 dye and more than 80% of the dye was removed within 15 min of reaction time. During the degradation process, an oxidation–reduction potential change from 196 to −577 mV was detected, indicating reductive condition is necessary for effective dye removal. FT-IR analysi... | We have constructed dichromatic matrices of property coefficients for all 1601 Aizu species. This involves 122 non-magnetic Aizu species and extends the work to the 773 species of phase transitions from disordered magnetic prototypic (parent) phases and the 616 species from ordered magnetic prototypic phases. In addition to coefficients describing the non-magnetic effects we have included the coefficients of pyromagnetic, magnetoelectric, piezomagnetic effects, and magnetic susceptibility. All components of these property tensors are displayed in 13 by 13 matrices; non-zero components of the prototypic phase are given in black and the spontaneous coefficients, that are non-zero in the ferroic phase and zero in the prototypic phase, are given in red. | eng_Latn | 27,948 |
New sandwich-type lanthanide complexes based on closed-macrocyclic Schiff base and phthalocyanine molecules | Two new sandwich-type lanthanide complexes with the general formula [(Pc)2Ln3(L)(OAc)(OCH3)2] (Ln(3+) = Dy(3+) () and Er(3+) ()) were successfully synthesized and structurally characterized based on closed-macrocyclic Schiff base and phthalocyanine molecules. The magnetic properties and structure-property relationship in this multi-decker system were investigated. Interestingly, the corresponding dysprosium complex shows typical single-molecule magnetic behavior with ferromagnetic dipole-dipole interactions and the slow relaxation of magnetization. | Abstract In this paper, we investigate the time-dependent Ginzburg–Landau (TDGL) equations coming from the superfluid atomic Fermi gases near the Feshbach resonance from the fermion–boson model. By the method of a priori estimates, we get the existence of global attractors in the case of BCS–BEC crossover. | eng_Latn | 27,949 |
Magnetic phase transition in La2−xSrxCuO4 around x=0.115 studied by La-NMR | The copper oxide superconductor La2−xSrxCuO4 shows x−TC curve with a small dip at x=0.115. In order to investigate the origin of this kink, the temperature dependence of 139La-NMR spectra has been studied. The significant broadening in the spectra was observed below 30K, suggesting the existence of the antiferromagnetic phase transition around x=0.115. | The metal atom in the title compound, [Cu(C7H5O3)2(C3H4N2)2], is coordinated by two O atoms (from two carboxylate anions) and two N atoms (from two N-heterocycles) in a square-planar geometry; it occupies a special position of site symmetry \overline{1}. Above and below the square are the hydroxy O atoms of adjacent molecules. This weak interaction [2.646 (2) A] leads to the formation of a linear chain; the chains are consolidated into a layer through hydrogen bonds. | eng_Latn | 27,950 |
High Temperature Superconducting (HTS) Coils for a Compact Spherical Tokamak | High temperature superconductors (HTSs) have the potential to impact the future development of superconducting applications for research magnets in physical sciences and industrial products. A compact spherical tokamak of major radius 25 cm has been designed and engineered using the second generation HTS material, REBCO tapes. It was developed with the primary objective to test out the feasibility of a fully superconducting device made entirely from HTS materials and hence be the first tokamak to demonstrate the practicality of this new medium operating at temperatures above 4.2 K. The tokamak has 6-D shaped toroidal field coils, and two poloidal field coils, each of which is wound in a pancake geometry. Each coil is made in one continuous winding and the coils are assembled together. Results of initial coils and magnet cooling and energisation will be presented. | We studied the role of the tensor interaction in He isotopes systematically on the basis of the tensor-optimized shell model (TOSM). We use a bare nucleon-nucleon interaction AV8${}^{\ensuremath{'}}$ obtained from nucleon-nucleon scattering data. The short-range correlation is treated in the unitary correlation operator method (UCOM). Using the TOSM + UCOM approach, we investigate the role of tensor interaction on each spectrum in He isotopes. It is found that the tensor interaction enhances the $LS$ splitting energy observed in ${}^{5}$He, in which the ${p}_{1/2}$ and ${p}_{3/2}$ orbits play different roles on the tensor correlation. In ${}^{6,7,8}$He, the low-lying states containing extra neutrons in the ${p}_{3/2}$ orbit gain the tensor contribution. On the other hand, the excited states containing extra neutrons in the ${p}_{1/2}$ orbit lose the tensor contribution due to the Pauli-blocking effect with the $2p2h$ states in the ${}^{4}$He core configuration. | eng_Latn | 27,951 |
Variational method study of the spin-1 Ising model with biaxial crystal-field anisotropy | The phase diagram of the spin-1 Ising model in the presence of a biaxial crystal-field anisotropy is studied within the framework of a variational approach, based on the Bogolyubov inequality for the free energy. We have investigated the effects of a transverse crystal-field $D_{y}$ on the phase diagram in the $T-D_{x}$ plane. Results obtained by using effective-field theory (EFT) on the honeycomb (% $z=3$), square ($z=4$) and simple cubic ($z=6$) lattices ($z$ is the coordination number) show only continuous phase transitions, while the variational approach presents first-order and continuous phase transitions for $D_{y}=0$% . We have also used the EFT for larger values of $z$ and we observe the presence of tricritical points in the phase diagrams, for $z\geq 7$, in accordance with the variational approach results. | Considering the time distance effect of blasting vibration and the quasi-static method, and making use of the improved slice method, this paper puts forward an analytic method of slope stability under blasting vibration; and gets a new computing technology of dynamic stability of slopes under blasting vibration. The calculation of an actual engineering example shows that the method is more reasonable and closer to the actuality than the conventional methods. | eng_Latn | 27,952 |
Influence of the crystal field on the magnetic behaviour of Er2Ni17 | Abstract The intermetallic Er2Ni17 was measured by 166Er Mossbauer spectroscopy. From the hyperfine field measured at T = 0.6 K we conclude that the two Er sites have almost pure | − 15 2 > and | − 13 2 > ground states. This behaviour can be explained by a different sign of the fourth order crystal field terms. | Abstract EPR investigations on light-emitting Manganese centres in device-near ZnS or ZnSe thin-film layers were done. Mn 2+ centres were detected in both basic modifications of ZnS. Assertion on the crystallinity could be made. The efficiency of EPR is demonstrated by some examples. | eng_Latn | 27,953 |
Mizrahi Subaltern Counterpoints: Sderot's Alternative Bands | This article addresses Mizrahi (or Oriental) identity in Israel by focusing on a well-known musical scene in the town of Sderot, in the south of Israel, populated largely by low-income Mizrahim. This group has undergone a unique Orientalization process in Israel. This process triggered the crystallization of a diverse musical scene in Sderot that exposed three practices of molding Mizrahi identity. By engaging with a dialectic model that appears in the later writing of Edward Said, I argue that the Mizrahi subversion of Israeli Orientalism encompasses a re-creation of it in different degrees of intensity. | We explain the basic physics behind oscillatory effects in superconductor/metallic ferromagnet (S/F) sandwiches, and describe the important effects of the spin orbit scattering in these systems. We find that spin-orbit scattering plays a major role in the physics of the superconducting proximity effect with a conducting ferromagnet. As examples, we present calculations of the T{sub c} of an S/F bilayer and the Josephson current (near T{sub c}) of an S/F/S trilayer. {copyright} {ital 1997} {ital The American Physical Society} | eng_Latn | 27,954 |
A New Density Operator Formalism for Describing Nuclear Magnetic Resonance Experiments | A density operator formalism has been proposed to describe the evolution of two-spin-1/2 systems in nuclear magnetic resonance experiments:The formalism is particularly convenient and has distinct physical meaning for describing the evolution of spin systems under the Hamiltonian containing non-commutable terms. Some examples are presented to demonstrate the new formalism. | We investigate the impact of the addition of nanoparticles (NP) on the fragility of a model glass-forming polymer melt by molecular dynamics simulations. We find significant changes in fragility for nanoparticle volume fractions $\phi$ exceeding $\approx$ 5%, where fragility changes correlate with the inverse variance of the magnitude of the Debye-Waller factor $$, a measure of local"stiffness"fluctuations. We also confirm the validity of the Buchenau relationship between $$ and the structural relaxation time $\tau$ for all $\phi$ and polymer-NP interaction types. | eng_Latn | 27,955 |
Synthesis, Structural and Magnetic Properties of the Solid Solution (CuCl1-xBrx)LaNb2O7 (0 <= x <= 1) | The two-dimensional (2D) quantum spin system (CuCl)LaNb 2 O 7 has a spin-singlet ground state with a gap of 2.3 meV, while the isostructural material (CuBr)LaNb 2 O 7 displays a collinear antiferromagnetic order at T N = 32 K. Here, we report on the synthesis of solid solution (CuCl 1- x Br x )LaNb 2 O 7 (0 ≤ x ≤1), and its structural and magnetic properties investigated by magnetic susceptibility, high-field magnetization, and neutron diffraction measurements. The x dependences of cell parameters follow Vegard's law, verifying the uniform distribution of Cl and Br atoms at the halide site, although a more complex structural evolution is inferred from an opposing correlation between the intra- and interlayer cell distances (vs x ). 5%-Br substitution is found to induce an antiferromagnetic order with T N = 7 K, consistent with recent µSR results, and the magnetic structure is collinear, having a significantly reduced moment. Further Br substitution leads to a linear increase in T N up to x = 1. These resu... | A horizontal thermal diffusion column was constructed and operated in the separation of CuSO{sub 4}-CoSO{sub 4}-H{sub 2}O, each salt being 0.5 molal. The equilibrium constant for mass transfer as 0.82 for separation of CuSO{sub 4} from water and 0.86 for CoSO{sub 4}. It was concluded that this method is suitable for separating the salt mixtures, the height of the transfer unit is proportional to the flow rate for total reflux operation, and the separation of each salt from water is independent of the other salt. (T.R.H.) | eng_Latn | 27,956 |
Normal and anomalous densities in Bose–Einstein condensates with optical lattices | We study the quantum phase transition from the superfluid to the Mott insulator state in two- and three-dimensional Bose–Einstein condensate with optical lattices using Bose–Hubbard Hamiltonian within the generalized Hatree–Fock–Bogoliubov approximation. The behavior of the depletion and the anomalous fraction has been investigated in the Mott insulator phase. We found that at T = 0, these quantities become significant in two and three dimensions. It is shown also that the dimensionality of the lattice enhances the anomalous density. | Abstract A layer of random defects in the simple cubic Ising model with nearest neighbor ferromagnetic interactions of strength J is considered. Using the real space renormalization group method we calculate defect free energy in the whole temperature range. Specifically, we analyze: the layer of diluted defects, the layer of spin-glass type defects, and the layer of mixed defects. The free energy is strongly dependent on the value of couplings between the defect and the bulk. | eng_Latn | 27,957 |
Leigh syndrome, a mitochondrial encephalo(myo)pathy: A review of the literature | Results of a literature survey of 173 patients with Leigh syndrome are presented, with emphasis on signs and symptoms in relation to age at onset, contributions of technical investigations to the diagnosis, pathophysiology, genetic considerations and therapeutic aspects. Based on this study we are of the opinion that it is possible to come to a diagnosis of "most probable Leigh syndrome" durante vitamin on the combination of clinical signs and symptoms, autosomal recessive mode of inheritance, association with a defect of energy metabolism, and CT or MRI abnormalities. | We present a computational study of 2$p$ core-level X-ray photoemission spectra of transition metal monoxides MO (M=Ni, Co, Mn) and sesquioxides M$_2$O$_3$ (M=V, Cr, Fe) using a theoretical framework based on the local-density approximation (LDA) $+$ dynamical mean-field theory (DMFT). We find a very good description of the fine spectral features, which improves considerably over the conventional cluster model. We analyze the role of the non-local screening and its relationship to the long-range magnetic order and the lattice geometry. Our results reveal the potential of the present method for the analysis and interpretation of the modern high-energy-resolution experiments. | eng_Latn | 27,958 |
Time Reversal Symmetry Breaking in noncentrosymmetric superconductor Re6Ti | We have investigated the superconducting state of the noncentrosymmetric superconductor Re6Ti (Tc = 6.0K) using a muon-spin rotation/relaxation technique. The zero-field muon experiment shows the presence of spontaneous magnetic fields in the superconducting state, indicating time-reversal symmetry breaking (TRSB). However, the low-temperature transverse-field muon measurements suggest nodeless s-wave superconductivity. Similar results were also observed for Re6X (X = Zr, Hf) family of materials which indicates that the pairing symmetry does not depend on the spin-orbital coupling. Altogether, these studies suggest an unconventional nature (TRSB) of superconductivity is intrinsic to the Re6X family of compounds and paves the way for further studies of this family of materials. | Abstract In the present article, we study the spin-dependent thermoelectric properties of a quantum dot connected to two ferromagnetic contacts. We obtain results for the conductance, thermopower, thermal conductance, Lorentz ratio and figure of merit. The transmission probability shows antiresonances as a function of the energy due to the quantum interference effects. It results in a violation of the Wiedemann-Franz law which produces an improvement of the spin-dependent thermopower and the merit figure of the system. This set up can be used to design new spin-dependent thermoelectric devices with high efficiencies. | yue_Hant | 27,959 |
Electrically tuneable directional coupling and switching based on multimode interference effect in dielectric loaded graphene plasmon waveguides | We have numerically demonstrated that electrically tuneable directional coupling and switching can be realized based on the multimode interference effect in dielectric-loaded graphene plasmon waveguides (DLGPWs) of our own design. The total field profile resulting from a superposition of all guided modes in the multimode dielectric-loaded graphene plasmon waveguide is electrically controllable because the propagation properties of the first three guided modes supported by the DLGPW can be effectively manipulated by electrostatic doping of graphene. The functional size of the device is only several micrometres, which is much smaller than the working wavelength. Such electrically controlled multifunctional devices may find potential applications in high-density integrated active plasmonic circuits. | In this work we investigate the quench dynamics in the Kondo model on the Toulouse line in the presence of a local magnetic field. It is shown that this setup can be realized by either applying the local magnetic field directly or by preparing the system in a macroscopically spin-polarized initial state. In the latter case, the magnetic field results from a subtlety in applying the bosonization technique where terms that are usually referred to as finite-size corrections become important in the present non-equilibrium setting. The transient dynamics are studied by analyzing exact analytical results for the local spin dynamics. The timescale for the relaxation of the local dynamical quantities turns out to be exclusively determined by the Kondo scale. In the transient regime, one observes damped oscillations in the local correlation functions with a frequency set by the magnetic field. | eng_Latn | 27,960 |
The variational symmetries and conservation laws in classical theory of Heisenberg (anti)ferromagnet | The non-linear partial differential equations describing the spin dynamics of Heisenberg ferro- and antiferromagnet are studied by Lie transformation group method. The generators of the admitted variational Lie symmetry groups are derived and conservation laws for the conserved currents are found via Noether's theorem. | We have evaluated, at different temperatures, the second and fourth order anisotropy constants of N%FeI,B- based melt spun samples in which Nd was partly replaced by Dy. This was done through an analysis of the first quadrant demagnetization branches of the hysteresis loops in terms of a one sublattice coherent rotation model of non interacting iso- tropically distributed grains. Our results evidence how the in- crease in Dy content corresponds both to the increase of the second order anisotropy constant and to a decrease of the fourth order one. | eng_Latn | 27,961 |
Measuring the interaction force between a high temperature superconductor and a permanent magnet | Repulsive and attractive forces are both possible between a superconducting sample and a permanent magnet, and they can give rise to magnetic levitation or free-suspension phenomena, respectively. We show experiments to quantify this magnetic interaction, which represents a promising field with regard to short-term technological applications of high temperature superconductors. The measuring technique employs an electronic balance and a rare-earth magnet that induces a magnetic moment in a melt-textured YBa2Cu3O7 superconductor immersed in liquid nitrogen. The simple design of the experiments allows a fast and easy implementation in the advanced physics laboratory with a minimum cost. Actual levitation and suspension demonstrations can be done simultaneously as a help to interpret magnetic force measurements. | AbstractNumerical studies of the Hubbard model and its strong-coupling form, the t-J model, show evidence for antiferromagnetic, ::: $$d_{x^{\text{2}} - y^2 } $$ ::: -pairing and stripe correlations which remind one of phenomena seen in the layered cuprate materials. Here, we ask what these numerical results imply about various scenarios for the pairing mechanism. | eng_Latn | 27,962 |
Phase Separation in RbxFe2-ySe2 Probed by Non-stoichiometry and Cu Doping | The paper presents M¨ ossbauer spectroscopy investigation on superconducting Rb0.8Fe1.6Se2 exhibit- ing nanoscale phase separation and two its deriva- tives: Cu-doped Rb0.8Fe1.56Cu0.04Se2 and Fe-deficient Rb0.7Fe1.4Se2. The spectra reveal the presence of the same dominant magnetic sextet in the samples, which is assigned to the Fe 16i sites of the √ 5 × √ 5 × 1 superstructure. This magnetic part is independent on the modification of the sample and does not undergo any changes after doping or deviation of stoichiometry. In contrast, the minor non-magnetic doublet in the spec- tra of Rb0.8Fe1.6Se2, which is attributed to the super- conducting nanoscale phase, is sensitive to such mod- ifications. After doping with Cu, the relative intensity of non-magnetic doublet significantly decreases together with suppression of superconductivity. On the other hand, the Fe-deficient sample is entirely magnetically ordered | Abstract A layer of random defects in the simple cubic Ising model with nearest neighbor ferromagnetic interactions of strength J is considered. Using the real space renormalization group method we calculate defect free energy in the whole temperature range. Specifically, we analyze: the layer of diluted defects, the layer of spin-glass type defects, and the layer of mixed defects. The free energy is strongly dependent on the value of couplings between the defect and the bulk. | eng_Latn | 27,963 |
Density Functional Theory Method for Study of the Mechanism of C–H Bond Formation on Finite-Sized Graphene Surface | The structures and electronic states of hydrogenated graphenes with a finite size have been investigated by a density functional theory (DFT) method. Five graphenes of various sizes (n=2, 4, 7, 14, and 19, where n indicates the number of benzene rings in graphene) were examined as models of a hydrogenated graphene system. The harmonic vibrational frequency corresponding to a C–H stretching mode showed a linear relationship between the frequency and the C–H bond length. The C–H bond formed by the addition of hydrogen atoms was completely polarized as Cδ-–Hδ+ in an equilibrium structure. It was found that the activation barrier is formed by hybridization from sp2 to sp3 in the transition region. The mechanism of C–H bond formation on a graphene surface was discussed on the basis of theoretical results. | A family of one-dimensional magnetic Hamiltonians is introduced, where at each site there are $n$ spin-$S$ operators. It is shown that, for special couplings between spins and for $S=\frac{1}{2}$, the model contains the complete spectrum of the Heisenberg chain with spins \textonehalf{}, 1, frac32;, etc., and the ground state is that of the corresponding Heisenberg chain. By the varying of a single parameter the model allows continuous transitions between chains with different spin. We map the spin-($S+S$) model onto the nonlinear $\ensuremath{\sigma}$ model and discuss the possibility of a finite gap in the spin-(\textonehalf{}+\textonehalf{}) model. | eng_Latn | 27,964 |
Disordered Ground State and Magnetic Field-Induced Long-Range Order in an S=3/2 Antiferromagnetic Honeycomb Lattice Compound Bi3Mn4O12(NO3) | Bi3Mn4O12(NO3), in which the Mn4+ ions carry S=3/2, is the first honeycomb lattice system that shows no long-range magnetic order. Using neutron scattering, we have determined that short-range antiferromagnetic correlations develop at low temperatures. Applied magnetic fields induce a magnetic transition, in which the short-range order abruptly expands into a long-range order. | Ambient temperature treatment of the new bulky formamidine (2,4,6-Me3C6H2)NC(H)NH(2,4,6-Me3C6H2), HFMes, with 0.5 or 1.0 equivalents of potassium hydride or potassium bis(trimethylsilyl)amide yields the first potassium formamidinate complex [K{(η6-Mes)NC(H)N(Mes)}{(η6-Mes)NHC(H)N(Mes)], which displays attenuated reactivity with respect to deprotonation and solvent replacement of the included HFMes ligand. | eng_Latn | 27,965 |
205Tl NMR study of vortex state of Tl2Ba2CuO6+δ | Abstract We report a 205 Tl NMR study of vortex state for an oriented polycrystalline sample of an overdoped high- T c superconductor Tl 2 Ba 2 CuO 6+δ ( T c ∼85 K) with magnetic field 2 T along the c -axis. An obvious Redfield pattern of the 205 Tl NMR spectrum for our sample at T =5 K indicates the vortex lattice state without local antiferromagnetic order at vortex cores. We emphasize that nonexponential nuclear spin-lattice relaxation curves indicate an imperfect vortex lattice or Bragg glass phase. | Ag-added Y–Ba–Cu–O bulk superconductors were joined using Ag-added Er–Ba–Cu–O solder and different Er211 contents. Microstructural analysis revealed that the volume fraction of Er211 at the joint with a composition of Er123:Er211 = 4:1 was the same as that for the expected volume fraction of the initial composition. That is, this composition seems to be optimum, since the mass balance was maintained during the crystal growth from the initial growth stage to the final stage. The trapped-field distribution for the joint using this composition was uniform and the only single peak indicated that strong coupling was achieved. | eng_Latn | 27,966 |
NiS - An unusual self-doped, nearly compensated antiferromagnetic metal | NiS, exhibiting a text-book example of a first-order transition with many unusual properties at low temperatures, has been variously described in terms of conflicting descriptions of its ground state during the past several decades. We calculate these physical properties within first-principle approaches based on the density functional theory and conclusively establish that all experimental data can be understood in terms of a rather unusual ground state of NiS that is best described as a self-doped, nearly compensated, antiferromagnetic metal, resolving the age-old controversy. We trace the origin of this novel ground state to the specific details of the crystal structure, band dispersions and a sizable Coulomb interaction strength that is still sub-critical to drive the system in to an insulating state. We also show how the specific antiferromagnetic structure is a consequence of the less-discussed 90 degree and less than 90 degree superexchange interactions built in to such crystal structures. | Abstract The spin-phonon spin 1 2 Heisenberg system is found to have the same critical index for the susceptibility as the ideal, rigid lattice ferromagnet. This is in accordance with the criterion for critical index renormalisation expounded by Fisher in terms of the sign of the specific heat index. | eng_Latn | 27,967 |
Spontaneous Tensor Properties for Multiferroic Phases | We have constructed dichromatic matrices of property coefficients for all 1601 Aizu species. This involves 122 non-magnetic Aizu species and extends the work to the 773 species of phase transitions from disordered magnetic prototypic (parent) phases and the 616 species from ordered magnetic prototypic phases. In addition to coefficients describing the non-magnetic effects we have included the coefficients of pyromagnetic, magnetoelectric, piezomagnetic effects, and magnetic susceptibility. All components of these property tensors are displayed in 13 by 13 matrices; non-zero components of the prototypic phase are given in black and the spontaneous coefficients, that are non-zero in the ferroic phase and zero in the prototypic phase, are given in red. | This note introduces the linear stability of a ferrofluid thick layer submitted to gravity and to a normal magnetic field. The compatibility condition is derived taking into account the Rayleigh-Taylor instability and the Marangoni one. The pure normal deformation is analytically solved and these results can be extended to explain the heat conducting case. © Copyright 2005 Walter de Gruyter. | eng_Latn | 27,968 |
Magnetic fields of cool active stars | Magnetic fields are present throughout the universe and are very important for many astrophysical processes. Magnetic field influences a star throughout its life and affects nearby objects such as ... | We explain the basic physics behind oscillatory effects in superconductor/metallic ferromagnet (S/F) sandwiches, and describe the important effects of the spin orbit scattering in these systems. We find that spin-orbit scattering plays a major role in the physics of the superconducting proximity effect with a conducting ferromagnet. As examples, we present calculations of the T{sub c} of an S/F bilayer and the Josephson current (near T{sub c}) of an S/F/S trilayer. {copyright} {ital 1997} {ital The American Physical Society} | eng_Latn | 27,969 |
Systematic evolution of the magnetotransport properties of Bi{sub 2}Sr{sub 2{minus}x}La{sub x}CuO{sub 6} with carrier concentration | We report that it is possible to obtain a series of high-quality crystals of Bi2Sr2−xLaxCuO6, of which the transport properties have been believed to be “dirtier” than those of other cuprates. In our crystals, the normal-state transport properties display behaviors which are in good accord with other cuprates; for example, in the underdoped region the in-plane resistivity ρabshows the pseudogap feature and in the overdoped region the T dependence of ρabchanges to Tnwith n>1. The characteristic temperatures of the pseudo-gap deduced from the resistivity and the Hall coefficient data are presented. | We present calculations for {sup 8}Be-{sup 8}Be cluster states in {sup 16}O based on our recent schematic coupled-channels model. We justify some of the approximations made in the schematic model in this paper. The present calculations broadly support our assumptions about the states in {sup 16}O which formed the basis of our previous calculations in {sup 24}Mg. {copyright} {ital 1996 The American Physical Society.} | eng_Latn | 27,970 |
[The interferon beta therapy after the first clinical episode of demyelination in multiple sclerosis]. | The currently available treatment of definite multiple sclerosis (MS) includes different preparations of interferon beta. Recently reported data of pathomorphological, MRI, MR-spectroscopy and immunohistochemical studies suggest that axonal damage secondary to inflammation appears at the very early stage of MS. Early pathological events can predict a future course of the disease. Inflammatory activity in relapsing MS does not confine to episodes of clinical impairment but often develops before the first episode and generally continues during remissions. Patients with clinically isolated syndrome (CIS) and an abnormal brain MRI scan are at high risk of developing clinically definite MS (CDMS). If the presence of lesions predisposes to MS, the number of lesions determines when disability will develop. The results of interferon beta trials in patients with CIS showed significant benefit of the treatment in decreasing risk of CDMS development. | We present a computational study of 2$p$ core-level X-ray photoemission spectra of transition metal monoxides MO (M=Ni, Co, Mn) and sesquioxides M$_2$O$_3$ (M=V, Cr, Fe) using a theoretical framework based on the local-density approximation (LDA) $+$ dynamical mean-field theory (DMFT). We find a very good description of the fine spectral features, which improves considerably over the conventional cluster model. We analyze the role of the non-local screening and its relationship to the long-range magnetic order and the lattice geometry. Our results reveal the potential of the present method for the analysis and interpretation of the modern high-energy-resolution experiments. | eng_Latn | 27,971 |
Proximity and Josephson effects with heavy-fermion superconductors | Abstract At an interface or junction, strong spin-orbit coupling with pairing inhomogeneity and small pair size on the heavy-electron side mean that coherent proximity or Josephson effects would occur for singlet to triplet as well as for singlet to singlet pairing states. | AbstractNumerical studies of the Hubbard model and its strong-coupling form, the t-J model, show evidence for antiferromagnetic, ::: $$d_{x^{\text{2}} - y^2 } $$ ::: -pairing and stripe correlations which remind one of phenomena seen in the layered cuprate materials. Here, we ask what these numerical results imply about various scenarios for the pairing mechanism. | eng_Latn | 27,972 |
시제작 DME 자동차의 VGT와 EGR의 적용에 관한 연구 | In this steady, mode tests(NEDC, CVS75) of proto-type common-rail DME vehicle were performed to investigate on the effect of EGR and VGT application. To these researches, VGT model , engine model and construction of engine calibration process for engine control set maps were performed . Also the limit A/F of a DME engine considering emitted CO concentrations and VGT mating property with DME engine. As the vehicle tests results, increasement of inlet air flow with VGT system reduced HC and CO concentrations, and application of EGR reduced NOx emission of DME vehicle. | We report a detailed investigation of GdO$_{1-x}$F$_{x}$FeAs (x = 0, 0.07 and 0.14) samples by means of high-field/high-frequency electron spin resonance (HF-ESR) together with measurements of thermodynamic and transport properties. The parent GdOFeAs compound exhibits Fe long-range magnetic order below 128 K, whereas both doped samples do not show such order and are superconducting with T$_c$ = 20 K (x = 0.07) and T$_c$ = 45 K (x = 0.14). The Gd$^{3+}$ HF-ESR reveals an appreciable exchange coupling between Gd and Fe moments, through which the static magnetic order is clearly seen in the parent compound. Owing to this coupling, HF-ESR can probe sensitively the evolution of the magnetism in the FeAs planes upon F doping. It is found that in both superconducting samples, where the Fe long-range order is absent, there are short-range, static on the ESR time scale magnetic correlations between Fe spins. Their occurrence on a large doping scale may be indicative of the ground states' coexistence. | kor_Hang | 27,973 |
Ferromagnetic resonance in β-p-NPNN at radio-frequency region | Abstract We performed the low-temperature and radio-frequency (rf) ESR of spherically molded single crystals of β-p-NPNN in order to re-investigate the ferromagnetic resonance (FMR). The symmetric FMR signals were clearly observed below 0.8 K for the first time. The resonance field for H//c is markedly shifted about 80 G higher than the EPR resonance field while the anisotropy of the resonance field is very weak when the magnetic field is applied within the ab-plane. These results clearly indicate the spin-hard axis is parallel to the c-axis. We estimate the magnetic anisotropy HK = 61 G using the FMR relation with uniaxial anisotropy. | 4 pages.-- PACS numbers: 05.45.Xt, 87.10.+e.-- ArXiv pre-print: http://arxiv.org/abs/nlin.CD/0512009.-- Final full-text version of the paper available at: http://dx.doi.org/10.1103/PhysRevE.73.055202. | eng_Latn | 27,974 |
Spin glass transitions of smectic-$A$ crosslinked elastomers | Elastomers are artificial polymeric materials created for industrial and commercial applications. Depending on their purpose, they are performing in different species and structure modifications. Our studies focus on the systems of elastomers randomly standing-distributed in a smectic $A$ (Sm$A$) liquid crystal. Basing on the suggestion following from the experiment, that at a phase transition from Sm$A$ to nematic phase caused by an increase of a crosslink concentration, such a system survives a percolation transition at low crossilink concentrations, we propose a modeling explaining this phenomena. We approve the three-dimensional Villain spin glass model and apply lattice Monte Carlo (MC) techniques on differential forms on a dual lattice, that is an alternative of a replica trick, developed for nematic elastomers in the 3D XY universality. In the results of that we have confirmed a concentration phase transition of percolation nature at a small crosslink concentration ($\sim$ 10 weight %). | Abstract The fabrication of high-quality Heusler alloy films with clear martensitic transformation is a challenging issue in the field of magnetic shape memory alloys. Here, flexible Mn-rich Ni–Mn–Sn (Mn49.9Ni40.4Sn9.7) thin films are successfully synthesized by pulsed laser deposition on mica substrates using Ti as buffer layer. XRD analysis reveals that films exhibit austenitic phase with L21 structure at room temperature. The surface morphology indicates polycrystalline structure of fine grains with size of about 60 nm and smooth surface with roughness of less than 1 nm. The temperature dependent magnetization measurement clearly confirms the existence of first-order martensitic transformation. Exchange bias was observed below 70 K with maximum exchange bias field of 148 Oe at 20 K, which is attributed to the exchange coupling between the coexisting antiferromagnetic and ferromagnetic phases due to the various occupations of Mn atoms. | eng_Latn | 27,975 |
NMR, magnetization, and heat capacity studies of the uniform spin-1/2 chain compound Bi6V3O16 | We report the local (NMR) and bulk (magnetization and heat capacity) properties of the vanadium-based S=1/2 uniform spin chain compound Bi6V3O16(Bi4V2O10.66). In the low-temperature {\alpha} phase, the magnetic ions (V4+) are arranged in one-dimensional chains. The magnetic susceptibility shows a broad maximum around 50 K signifying a short-range magnetic order. Heat capacity measurements also reveal low-dimensional magnetism. The 51V magic angle spinning nuclear magnetic resonance measurements clearly show that the magnetic V4+ and nonmagnetic V5+ species are located on different crystallographic sites with no mixed occupation. The spin susceptibility calculated from the shift of the 51V NMR spectra reproduces the behavior observed in magnetic susceptibility and agrees well with the S=1/2 uniform spin chain model with J=113(5) K. | Abstract This work is aimed at examining how the tetragonality of Zn x Mn 3− x O 4 spinel structures depends on the chemical composition when Zn x Mn 3− x O 4 is embedded in a metal matrix. The paper focuses on a wide range of Zn x Mn 3− x O 4 precipitates in a Ag matrix with x varying between 0 and 1.5. This variation of x has been obtained by internal oxidation of Ag–2at.%Mn–4at.%Zn in air followed by annealing in vacuo at different temperatures. It will be demonstrated that the Zn concentration x in Zn x Mn 3− x O 4 has a major influence on the interfacial misfit and orientation relation between Ag/Zn x Mn 3− x O 4 . The degree of mismatch of 10.4% of {1 1 1} Ag–Mn 3 O 4 and 2.4% of Ag–Zn 1.5 Mn 1.5 O 4 was visualized using the Bragg filtering technique on HRTEM micrographs of those interfaces. It was possible to identify misfit dislocations qualitatively with this technique at {1 1 1} Ag–Zn x Mn 3− x O 4 interfaces with different degree of mismatch. | eng_Latn | 27,976 |
QUANTUM XY SPIN GLASS WITH FERROMAGNETIC COUPLING IN EXTERNAL FIELD | The quantum XY spin glass model with ferromagnetic coupling in an external field is investigated numerically. The susceptibility exhibits the typical spin glass feature, the cusp of the transverse susceptibility corresponding to the phase transition is shifted to lower temperature by increasing field. In addition to the crossover feature observed in CuMn, the specific heat exhibits the 2-dimensional Ising model-like feature. | ABSTRACTThis paper aims to develop, assess, and numerically implement analytical models for the newly introduced Quintuple Friction Pendulum Isolator (QFPI) which can identically capture its real e... | yue_Hant | 27,977 |
Low-power decoupling in fast magic-angle spinning NMR | We investigate the possibility of a low-power rf-irradiation approach to heteronuclear spin decoupling in solid-state NMR under high-frequency magic-angle sample spinning. Decoupling is achieved by applying an rf-field with an amplitude corresponding to a precession frequency much lower than the spinning frequency. This leads to a reversal of the averaging processes compared to normal high-power continuous-wave decoupling. Such an approach becomes increasingly interesting with increasing MAS spinning frequency. In rigid solids, low-power decoupling becomes competitive above about 40 kHz MAS frequency. | The structure of GMA is introduced. Static displacement-force model and magnetism-machine coupling model for helping understand the magnetostriction and establishes simulation model are given. Simulation result shows that response time of machine part is slowness. It brings some disbennifit affection if minish damp. For example,exceed quantity and undulation will argument. It is important to ameliorate dynamic characteristic of the system to append a reasonable adjustor. | eng_Latn | 27,978 |
Side-chains configurations in coiled coils revealed by the 5.15-A meridional reflection on hard alpha-keratin X-ray diffraction patterns. | The origin of the 5.15-A meridional reflection on hard alpha-keratin X-ray diffraction patterns is discussed in terms of side-chains conformations. We show it to reveal specific configurations of the side chains which are common to all two-stranded alpha-helical coiled coils. Combining literature data on crystallised coiled coil pieces and molecular dynamics results with our X-ray diffraction pattern simulations, we propose rules for the attribution of chi1 torsion angles for coiled coils involved in fibres whose structure cannot be resolved at atomic resolution: in a (a b c d e f g) heptad repeat, a and d residues, respectively, adopt mean t and g+ configurations, whereas statistical rules are given for the other residues. | The symmetries of paramagnons can be determined by considering the transformation properties of the appropriate wave-like magnetic-excitation creation operators. With the known symmetries of the magnons below the Neel temperature of an antiferromagnet it is possible to determine, in many cases unambiguously, the symmetries of the paramagnons above the Neel temperature. The method is illustrated by determining the symmetries of paramagnons in MnF2 and NiF2. | eng_Latn | 27,979 |
Magnetic properties of Pr[Fe(CN)6] · 5H2O | Magnetic properties of Prussian blue analogues, the molecule-based ferrimagnet Pr[Fe(CN) 6 ].5H 2 0, are presented. The zero-field-cooled magnetisation curves deviate from the field-cooled magnetisation measurements M(T) below certain temperature T f = 14.5 K, and show a broad maximum at about T = 12 K. Such a behaviour of M(T) is typical for the small particles system or for non-interacting magnetic clusters. The saturation magnetic moment μ s = 2.02 μ B , determined from M(1/H) curves, agrees very well with the theoretical value. The Curie temperature T c = 14.8 K were determined from M 2 (T) curves. The M(H) curve shows hysteresis behaviour at T = 4.5 K. Magnetic susceptibility χ obeys Curie-Weiss law very well above T = 30 K with μ eff = 3.8 μ B and θ = -18.6 K. The changes in shapes of low-temperature 1 H-solid-echo spectra reflect the changes in the magnetic state of the sample. | Abstract New EPR centres for Ce 3+ , Nd 3+ and Sm 3+ in CaF 2 with tetragonal symmetry are reported where charge compensation is due to interstitial H - or D - ions. The strength of these centres has been correlated with the i.r. local mode absorption of the paired hydrogen. | eng_Latn | 27,980 |
Nonlinear Dynamics of an Array of Nano Spin Transfer Oscillators | The dynamics of a macrospin variable representing homogeneous magnetization of the free layer of a nanospin transfer oscillator (STNO) can be represented by the Landau–Lifshitz–Gilbert–Slonczewski (LLGS) equation. This is a generalization of the evolution equation of a ferromagnetic spin system represented by the Heisenberg interaction. STNO is a fascinating nonlinear system exhibiting an interesting bifurcation-chaos scenario depending up on the nature of the applied external magnetic field and the spin current. In order to enhance the microwave power generated by STNOs, recently it has been suggested to consider series and parallel arrays of STNOs with appropriate couplings so that the oscillators get synchronized. We show here the interesting possibility of obtaining synchronization with a common external periodically varying applied magnetic field. We also study the mass synchronization in arrays of STNOs represented by phase oscillators and study the underlying properties. | The main result of this paper identities certain derived cones to the reachable sets of nonsmooth control systems in terms of quasitangent variational inclusions that generalize the classical variational equation in the theory of O.D.E.. This result extends to nonsmooth control systems an earlier result of the second author. | eng_Latn | 27,981 |
Pseudo-Spin Model for the Cytoskeletal Microtubule Surface | Due to the inherent symmetry structures and the electric properties in the microtubule (MT), we treat the MT as a one-dimensional ferroelectric system and describe the nonlinear dynamics of dimer electric dipoles in one protofilament of the MT by virtue of the double-well potential. Consequently, the physical problem has been mapped onto the pseudo-spin system, and the mean-field approximation has been taken to obtain some physical results, including the expression for the phase transition temperature Tc and the estimated value of Tc (=312 K). | Abstract The spatial configuration of the polysaccharide chain of chitin is discussed. It is concluded that the only arrangement which is sterically satisfactory and fits X-ray diffraction data is that of a “bent” chain. | eng_Latn | 27,982 |
Synthesis and reactions of β-diketiminate-supported complexes with Mg–Fe or Yb–Fe bonds | Reaction of [M(NacNac)I(THF)]n (M = Mg, Ca or Yb; n = 1 or 2) with KFp gave Mg(NacNac)Fp(THF) (, Mg-Fe = 2.6326(4) Å) or [M(NacNac)(μ-Fp)(THF)]2 (M = Ca or Yb (10), no M-Fe bonds); reaction of with [YbFp2(THF)3]2 gave [{Yb(NacNac)(THF)}2(μ-YbFp4)] (Yb-Fe = 2.9758(5)-3.1702(5) Å) containing the first example of a lanthanide bound solely to four transition metals; reaction of with TolNCNTol gave Mg(NacNac){(NTol)2CFp} via the first net insertion of an unsaturated substrate into an alkaline earth-transition metal bond (NacNac = HC{C(Me)N(2,6-C6H3(i)Pr2)}2; Fp = CpFe(CO)2; Tol = 4-C6H4Me). | Complete magnetoelectric (ME) phase diagrams of orthorhombic $R$MnO$_{3}$ with and without magnetic moments on the $R$ ions have been established. Three kinds of multiferroic ground states, the $ab$-cycloidal, the $bc$-cycloidal, and the collinear $E$-type phases, have been identified by the distinct ME responses. The electric polarization of the $E$-type phase dominated by the symmetric spin exchange ($bm{S}_{i} cdot bm{S}_{j}$) is more than 10 times as large as that of the $bc$-cycloidal phase dominated by the antisymmetric one ($bm{S}_{i} times bm{S}_{j}$), and the ME response is enhanced near the bicritical phase boundary between these multiferroic phases of different origins. These findings will provide an important clue for the development of the magnetically induced multiferroics. | eng_Latn | 27,983 |
A new method of producing the magnetic refrigerant suitable for the ericsson magnetic refrigeration | A layer structural complex magnetic refrigerant, which is suitable for the Ericsson cycle, satisfying the Carnot principle, has been investigated. Above ∼ 15 K, since the thermal agitation energy and the lattice entropy increase considerably, the ferromagnetic material has to be used for the refrigerant in the magnetic refrigeration. However, the variation of the magnetic entropy of the ferromagnets is not appropriate to the Ericsson cycle in which the entropy difference ΔS J between two kinds of the isomagnetic field processes should be constant in the refrigeration range. In order to make the refrigerant having constant ΔS J mentioned above, we made the layer structural sintered material composed of four kinds of ferromagnets, ErAl 2.2 , HoAl 2.2 , (Dy 0.5 Ho 0.5 )Al 2.2 and DyAl 2.2 , and investigated its entropy experimentally. As the result, it is verified that the layer structural magnetic material is one of the most promising refrigerant for the Ericsson cycle. | In this work we present the results of theoretical analysis of the de Haas-van Alphen oscillations in quasi-two-dimensional conductors. We have been studying the effect of the Fermi-liquid correlations of charge carriers on the above oscillations. It was shown that at reasonably low temperatures and weak electron scattering the Fermi-liquid interactions may cause noticeable changes in both amplitude and shape of the oscillations even at realistically small values of the Fermi-liquid parameters. Also, we show that the Fermi-liquid interactions in the system of the charge carriers may cause magnetic instability of a quasi-two-dimensional conductor near the peaks of quantum oscillations in the electron density of states at the Fermi surface, indicating the possibility for the diamagnetic phase transition within the relevant ranges of the applied magnetic fields. | eng_Latn | 27,984 |
Anisotropic exchange within decoupled tetrahedra in the quantum breathing pyrochlore Ba3Yb2Zn5O11 | The low energy spin excitation spectrum of the breathing pyrochlore Ba3Yb2Zn5O11 has been investigated with inelastic neutron scattering. Several nearly resolution limited modes with no observable dispersion are observed at 250 mK while, at elevated temperatures, transitions between excited levels become visible. To gain deeper insight, a theoretical model of isolated Yb3+ tetrahedra parametrized by four anisotropic exchange constants is constructed. The model reproduces the inelastic neutron scattering data, specific heat, and magnetic susceptibility with high fidelity. The fitted exchange parameters reveal a Heisenberg antiferromagnet with a very large Dzyaloshinskii-Moriya interaction. Using this model, we predict the appearance of an unusual octupolar paramagnet at low temperatures and speculate on the development of inter-tetrahedron correlations. | This paper is aimed at dissecting and discussing the effect of high pressure on chirogenesis, thus unveiling the role of this universal force in astrochemical and primeval Darwinian scenarios. The first part of this contribution revisits the current status and recent experiments, most dealing with crystalline racemates, for which generation of metastable conglomeratic phases would eventually afford spontaneous resolution and hence enantioenriched mixtures. We then provide an in-depth thermodynamic analysis, based on previous studies of non-electrolyte solutions and dense mixtures accounting for the existence of positive excess volume upon mixing, to simulate the mirror symmetry breaking, the evolution of entropy production and dissipation due to enantiomer conversion. Results clearly suggest that mirror symmetry breaking under high pressure may be a genuine phenomenon and that enantioenrichment from initial scalemic mixtures may also take place. | eng_Latn | 27,985 |
Magnetic properties of Ho2(Co1-x Fex)17 compounds | The structure and magnetic properties of Ho2(Co1-xFex)17 compounds with x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.6, 0.8 or 1.0 have been investigated by x-ray diffraction (XRD) and magnetization measurements. XRD patterns demonstrate that all samples are single phase with the hexagonal Th2Ni17-type structure. The substitution of Fe for Co initially leads to a increase in the lattice constant a and unit cell volumes v and then a small decrease. The Curie temperatures decrease monotonously with increasing Fe concentration. Saturation magnetization increases with x and then decreases, attaining a maximum at x = 0.2. The magnetic anisotropy phase diagram of Ho2(Co1-xFex)17 compounds has been determined from the temperature dependence of magnetization and the XRD patterns of magnetically oriented powder samples. The spin-reorientation temperature of Ho2(Co1-xFex)17 compounds is found to decrease with increasing Fe content for x 0.3, attaining a lowest value of 248 K at x = 0.3. | The hyperfine coupling constants and the natural radiative lifetimes of the 5 p 2 P 3/2 and 6 p 2 P 3/2 levels of K 39 were determined in a level crossing experiment on an enriched K 39 sample in a sealed-off resonance cell. The following results were obtained: ----- -- a (5 p 2 P 3/2 ) = 1.973 (12) MHz -- a (6 p 2 P 3/2 ) = 0.886 (8) MHz ----- -- b (5 p 2 P 3/2 ) = 0.870 (18) MHz -- b (6 p 2 P 3/2 ) = 0.370 (15) MHz ----- -- I(5 p 2 P 3/2 ) = 133 (3) ns -- I(6 p 2 P 3/2 ) = 310 (15) ns ----- Considering the influence of core polarization on the magnetic hyperfine interaction and applying a Sternheimer correction, fairly consistent values of the electric quadrupole moment Q are obtained from the first three levels of the np 2 P 3/2 sequence. We find Q (K 39 ) = +0.059 (6) barn. | eng_Latn | 27,986 |
Disclination classes, fractional excitations, and the melting of quantum liquid crystals | We consider how fractional excitations bound to a dislocation evolve as the dislocation is separated into a pair of disclinations. We show that some dislocation-bound excitations (such as Majorana modes and half-quantum vortices) are possible only if the elementary dislocation consists of two inequivalent disclinations, as is the case for stripes or square lattices but not for triangular lattices. The existence of multiple inequivalent disclination classes governs the two-dimensional melting of quantum liquid crystals (i.e., nematics and hexatics), determining whether superfluidity and orientational order can simultaneously vanish at a continuous transition. | Abstract A layer of random defects in the simple cubic Ising model with nearest neighbor ferromagnetic interactions of strength J is considered. Using the real space renormalization group method we calculate defect free energy in the whole temperature range. Specifically, we analyze: the layer of diluted defects, the layer of spin-glass type defects, and the layer of mixed defects. The free energy is strongly dependent on the value of couplings between the defect and the bulk. | eng_Latn | 27,987 |
Transition Metal Complexes With Perfluorinated Ligands. | Abstract : We have continued to make progress in preparing transition metal complexes containing fluorinated ligands, and have completed several sub-projects. We have prepared the first examples of transition metal compounds containing tetrafluoroethylene ligands that rotate rapidly on the NMR time scale. This is a significant discovery en route to a transition metal catalyst that will promote the Ziegler-Natta polymerization of fluorinated olefins to give high polymers. The factors governing the barrier to fluoroolefin rotation have been identified. We have synthesized the first example of a transition metal complex containing the pentafluorocyclopentadienyl ligand. This is an important ligand that may improve the thermal robustness of many transition metal compounds. (jg) | (Received 19 June 2011 ; in final form 25 February 2012) Abstract In this study, we investigated the spin dependent electronic transport of a fishbone-like nanostructure including two magnetic atoms at its ends. The electronic conductance of this nanostructure for three different orientations of atomic magnetic moments was numerically studied when the structure was sandwiched between two nonmagnetic leads. By using Green’s function technique at the tight-binding model, we calculated the spin dependent electronic transmission coefficient. The calculated results revealed that the conductance depends on the incident electron energy as well as the magnitude and orientation of atomic magnetic moments in the nanostructure. | eng_Latn | 27,988 |
Modelling the cyclic ratcheting of sands through memory-enhanced bounding surface plasticity | The modelling and simulation of cyclic sand ratcheting is tackled by means of a plasticity model formulated within the well-known critical state, bounding surface SANISAND framework. For this purpo... | We study in this paper the properties of a two-body random matrix ensemble for distinguishable spins. We require the ensemble to be invariant under the group of local transformations and analyze a parametrization in terms of the group parameters and the remaining parameters associated with the 'entangling' part of the interaction. We then specialize to a spin chain with nearest-neighbour interactions and numerically find a new type of quantum-phase transition related to the strength of a random external field, i.e. the time-reversal-breaking one-body interaction term. | eng_Latn | 27,989 |
Magnetothermopower of Fe / Cr superlattices | Abstract We report magnetothermopower S(H) measurements at room temperature for sputtered [Fe(32 A) / Cr(x)]30 superlattices with x ≈ 5–50 A. The thermopower in zero field S(H = 0) appears to extrapolate to the known values for Fe and Cr in the x = 0 and large-x limits, respectively, and drops below these values at intermediate x. S follows the same trend with H and x as the magnetoresistance (MR), which shows oscillatory behavior as a function of x, and large field effects for antiferromagnetic Fe interlayer couplings. Both S(H) and the MR saturate when the applied field aligns the magnetization of the Fe-layers parallel to each other, but the thermopower is enhanced by application of a magnetic field, while the resistivity decreases, in accord with expectation. | ABSTRACTThis letter is motivated by an apparent paradox, in that some quaternary systems (particularly in the Ti–Zr–Al–C system) have been shown to exhibit M-site out-of-plane ordering, while prior work and calculations by the present authors suggest endothermic interactions between Zr and Ti. In this letter we provide a resolution to this issue and provide a more extended analysis on the out-of-plane and in-plane ordering in the M sites of quaternary MAX alloys. The results provide further insights to develop criteria to predict potential out-of-plane ordering tendencies in other MAX systems.fx1 | eng_Latn | 27,990 |
Thrombophlebitis migrans: a further systemic complication of ulcerative colitis. | Thrombophlebitis migrans complicating ulcerative colitis has been reported only once previously when it occurred in a patient with chronic and extensive bowel disease. This report describes the occurrence of thrombophlebitis before any bowel upset in a patient who proved to have only a mild colitis, and no laboratory evidence of hypercoagulability. It seems that thrombophlebitis migrans is a further systemic complication of ulcerative colitis, and that its occurrence may precede overt bowel disease. | Since the discovery of all-optical magnetization switching in rare-earth transition-metal alloys the underlying magnetization dynamics of multisublattice magnets has become a hot topic of modern magnetism. We studied the ultrafast magnetization dynamics in TbCo alloys as a function of the alloy composition and the laser fluence using either 800 nm or 400 nm probe pulses. Direct comparison between TbCo samples with different compositions for equal excitation conditions demonstrates that the magnetization dynamics of the Co sublattice strongly depends on the Tb concentration. For Tb32Co68 the magnetization of the sublattices can even transiently be reversed on a subpicosecond time scale. | eng_Latn | 27,991 |
Structure and Magnetic Properties of Trinuclear Copper(II) Complex [Cu 3 (bipy) 6 (μ 3 -CO 3 )][B 12 H 12 ] 2 ∙4.5DMF∙2H 2 O | Abstract Trinuclear copper(II) complex [CuII3(bipy)6(μ3-CO3)][B12H12]2·4.5DMF·2H2O is isolated as a result of the redox reaction proceeding when [AgI2B12H12] was allowed to react with CuICl in the presence of bipy. Crystal structure, magnetic properties, and EPR spectrum of the compound are studied. It has been found that in the range 300–2 K, magnetic moment decreases from 1.98 to 1.33 µB with decreasing the temperature. In the EPR spectrum, the transition ΔM = ±3 transition is observed indicating the existence of the S = 3/2 state. This transition is explained by the effect of fine coupling tensor which admixes the |−1/〉 state into the |3/2〉 state and the |1/2〉 state into the |−3/2〉 state. The EPR spectrum is simulated by the spin Hamiltonians for S = 3/2 and S = 1/2. | The paper studies the behaviour of the Mn spin for dilute Mn in Pt as a function of temperature and applied field using the technique of nuclear orientation. In the preferentially oriented cubic polycrystalline foil a preferential nuclear spin ordering axis has been observed in the absence of an applied field. A measure of interaction of the spin with its environment has been obtained which may be modelled by a molecular field with mean value 440 G, and having a distribution in magnitude and direction. The saturation hyperfine field for Mn in Pt was found to be -365+or-15 kG. | kor_Hang | 27,992 |
A nickel(II) complex catalyzed electroreductive cyclization of allyloxy radicals via 1,5-hydrogen shift | Tandem radical-mediated epoxide fragmentation, radical translocation, and cyclization to form cyclopentanols and cis-fused bicyclic compounds have been studied by a nickel(II) complex catalyzed electroreduction. | Based on density functional calculations, we present a detailed theoretical study of the electronic structure and the magnetic properties of the quasi-one dimensional chain cuprate Li_2ZrCuO_4 (Li_2CuZrO_4). For the relevant ratio of the next-nearest neighbor exchange J_2 to the nearest neighbor exchange J_1 we find alpha = -J_2/J_1 = 0.22\pm0.02 which is very close to the critical point at 1/4. Owing this vicinity to a ferromagnetic-helical critical point, we study in detail the influence of structural peculiarities such as the reported Li disorder and the non-planar chain geometry on the magnetic interactions combining the results of LDA based tight-binding models with LDA+U derived exchange parameters. Our investigation is complemented by an exact diagonalization study of a multi-band Hubbard model for finite clusters predicting a strong temperature dependence of the optical conductivity for Li_2ZrCuO_4. | eng_Latn | 27,993 |
Compressibility of a two-dimensional electron gas in a parallel magnetic field | The thermodynamic compressibility of a two-dimensional electron system in the presence of an in-plane magnetic field is calculated. We use accurate correlation energy results from quantum Monte Carlo simulations to construct the ground state energy and obtain the critical magnetic field Bc required to fully spin polarize the system. Inverse compressibility as a function of density shows a kink-like behavior in the presence of an applied magnetic field, which can be identified as Bc. Our calculations suggest an alternative approach to transport measurements of determining full spin polarization. | Abstract The effect of aromatic hydrocarbon (benzene, C 6 H 6 ) addition on lattice parameters, microstructure, critical temperature ( T c ), critical current density ( J c ) of bulk MgB 2 has been studied. In this work only 2 mol% C 6 H 6 addition was found to be very effective in increasing the J c values, while resulting in slight reduction of the T c . J c values of 2 mol% C 6 H 6 added MgB 2 bulks reached to 1.83×10 6 A/cm 2 at 15 K and 0 T. Microstructural analyses suggest that J c enhancement is associated with the substitution of carbon with boron and which also results in the smaller MgB 2 grain size. The change in the lattice parameters or the lattice disorder is claimed as a cause of the slight reduction in the T c by carbon addition. We note that our results show the advantages of C 6 H 6 addition include homogeneous mixing of precursor powders, avoidance of expansive nanoadditives, production of highly reactive C , and significant enhancement in J c of MgB 2 , compared to un-doped samples. | eng_Latn | 27,994 |
Quantum spin and charge pumping through double quantum dots with ferromagnetic leads | Abstract The pumping of electrons through double quantum dots (DQDs) attached to ferromagnetic leads have been theoretically investigated by using the nonequilibrium Greenʼs function method. It is found that an oscillating electric field applied to the quantum dot may give rise to the pumped charge and spin currents. In the case that both leads are ferromagnet, a pure spin current can be generated in the antiparallel magnetization configuration, where no net charge current exists. The possibility of manipulating the pumped spin current is explored by tuning the dot level and the ac field. By making use of various tunings, the magnitude and direction of the pumped spin current can be well controlled. For the case that only one lead is ferromagnetic, both of the charge and spin currents can be pumped and flow in opposite directions on the average. The control of the magnitude and direction of the pumped charge and spin currents is also discussed by means of the magnetic flux threading through the DQD ring. | Abstract Here we report a detailed study of organic light-emitting diodes based on poly(9,9-dioctylfluorene) (PFO), to investigate polaron generation, due to field induced singlet dissociation, and their subsequent recombination. We find that initially free polarons coalesce into intermediate pairs of both singlets and triplets multiplicity which subsequently decay into the neutral state. There is indication that the efficiency of singlet formation ( β =0.7) is much higher than expected from simple state degeneracy arguments ( β =0.25). | eng_Latn | 27,995 |
Spectrophotometric Determination of Molybdenum(VI) with 5'-Nitro-Salicylfluorone and Its Application | 5'-Nitrosalicylfluorone(5'-NSF)was used as chromogenie reagent in the spectrophotometric determination of molybdenum(Ⅵ).In a dil.H_3 PO_4 medium and in the presence of non-ionic surfactant OP,a stable and orangered colored complex was formed between Mo(Ⅵ)and 5'-NSF,with absorption maxima at the wavelength of 528 nm,and molar absorptivity(e528)of 1.22×10~5L·mol~(-1)·cm~(-1).Beer's law was kept with concentration of Mo(Ⅵ)within 0.30 mg·L~(-1).The proposed method has been used in the determination of mieroamounts of molybdenum in carbon steel and low alloy steel containing no or small amounts of tungsten and titanium giving results in consistency with the standard values. | We have performed high-throughput characterization of composition-spread La 1-x Ca x MnO 3 (LCMO) and Nd 1-x Sr x MnO 3 (NSMO) films, fabricated by the precursor technique, with a scanning SQUID microscope (SSM). In both films, SSM successfully observed spatial variation of magnetic field, corresponding to magnetic phase transitions with respect to chemical composition. The obtained magnetic phase diagrams basically reproduced those reported in bulk materials. However, several distinctive differences have also been noted. For instance, the region identified as a charge ordered insulator in LCMO revealed intense field, suggesting the occurrence of phase separation into ferromagnetic and non-magnetic states. These results confirm that SSM possesses sufficient analytical performance for high-throughput characterization of combinatorial magnetic libraries in composition spread form. | eng_Latn | 27,996 |
Susceptibility of compressible Heisenberg ferromagnet | Abstract The spin-phonon spin 1 2 Heisenberg system is found to have the same critical index for the susceptibility as the ideal, rigid lattice ferromagnet. This is in accordance with the criterion for critical index renormalisation expounded by Fisher in terms of the sign of the specific heat index. | We have studied segregation and embrittling energy of sp ::: elements of the 3rd, 4th and 5th period (Al, Si, P, S, Ga, Ge, ::: As, Se, In, Sn, Sb and Te) at the Sigma5(210) grain boundary ::: (GB) in fcc nickel and the segregation of these impurities at ::: the (210) free surface (FS). Full relaxation of the geometric ::: configuration of the GB and FS without and with impurities has ::: been performed and the effect of impurities on the distribution ::: of magnetic moments has been analysed. We determined the ::: embrittling energy from the difference between the GB and FS ::: binding energies on the basis of the Rice Wang model. and we ::: separated embrittling energy into the chemical and mechanical ::: part. | eng_Latn | 27,997 |
Perovskite Manganites Hosting Versatile Multiferroic Phases with Symmetric and Antisymmetric Exchange Strictions | Complete magnetoelectric (ME) phase diagrams of orthorhombic $R$MnO$_{3}$ with and without magnetic moments on the $R$ ions have been established. Three kinds of multiferroic ground states, the $ab$-cycloidal, the $bc$-cycloidal, and the collinear $E$-type phases, have been identified by the distinct ME responses. The electric polarization of the $E$-type phase dominated by the symmetric spin exchange ($bm{S}_{i} cdot bm{S}_{j}$) is more than 10 times as large as that of the $bc$-cycloidal phase dominated by the antisymmetric one ($bm{S}_{i} times bm{S}_{j}$), and the ME response is enhanced near the bicritical phase boundary between these multiferroic phases of different origins. These findings will provide an important clue for the development of the magnetically induced multiferroics. | We present a computational study of 2$p$ core-level X-ray photoemission spectra of transition metal monoxides MO (M=Ni, Co, Mn) and sesquioxides M$_2$O$_3$ (M=V, Cr, Fe) using a theoretical framework based on the local-density approximation (LDA) $+$ dynamical mean-field theory (DMFT). We find a very good description of the fine spectral features, which improves considerably over the conventional cluster model. We analyze the role of the non-local screening and its relationship to the long-range magnetic order and the lattice geometry. Our results reveal the potential of the present method for the analysis and interpretation of the modern high-energy-resolution experiments. | eng_Latn | 27,998 |
Fano-Rashba effect and enhancement of figure of merit and violation of Wiedemann-Franz law | Abstract In the present article, we study the spin-dependent thermoelectric properties of a quantum dot connected to two ferromagnetic contacts. We obtain results for the conductance, thermopower, thermal conductance, Lorentz ratio and figure of merit. The transmission probability shows antiresonances as a function of the energy due to the quantum interference effects. It results in a violation of the Wiedemann-Franz law which produces an improvement of the spin-dependent thermopower and the merit figure of the system. This set up can be used to design new spin-dependent thermoelectric devices with high efficiencies. | For a large class of vanilla contingent claims, we establish an explicit F\"ollmer-Schweizer decomposition when the underlying is a process with independent increments (PII) and an exponential of a PII process. This allows to provide an efficient algorithm for solving the mean variance hedging problem. Applications to models derived from the electricity market are performed. | eng_Latn | 27,999 |
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