共查询到20条相似文献,搜索用时 15 毫秒
1.
This paper reports on the results of ab initio spin-polarized GW calculations of quasiparticle properties, such as the spectral weight, the lifetime, the velocity, and the mean free path, for the FeCo ferromagnetic alloy and its components. The contribution of the localized d states to the above characteristics has been analyzed. The spin asymmetry of the properties of quasiparticle excitations, which is responsible for the spin filter effect observed in experiments, has been investigated. The contributions to the mean free path from the electron scattering processes, which are disregarded within the framework of the GW approximation, have been estimated from a comparison with experimental data. 相似文献
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A. V. Samokhvalov S. N. Vdovichev B. A. Gribkov S. A. Gusev A. Yu. Klimov Yu. N. Nozdrin V. V. Rogov A. A. Fraerman S. V. Egorov V. V. Bol’ginov A. B. Shkarin V. S. Stolyarov 《JETP Letters》2012,95(2):104-113
Experimental and theoretical studies of ferromagnet-superconductor hybrid systems consisting of a Josephson junction placed in the nonuniform field of submicron ferromagnetic particles are reviewed. 相似文献
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A. V. Zdoroveyshchev M. V. Dorokhin O. V. Vikhrova P. B. Demina A. V. Kudrin A. G. Temiryazev M. P. Temiryazeva 《Physics of the Solid State》2016,58(11):2267-2270
The magnetic properties of Co45Pt55 films deposited by electron-beam evaporation in vacuum have been studied. The measurements of the Faraday and Kerr magnetooptical effects confirm the presence of the easy-magnetization axis perpendicular to the Co45Pt55 surface. It is shown that the perpendicular magnetic anisotropy and the residual magnetization are retained at 300 K for a long time. The magnetic characteristics of the Co45Pt55 layer surface have been studied by magnetic force microscopy, and “circular” mobile magnetic structures have been detected. The spin light-emitting diodes based on In(Ga)As/GaAs heteronanostructures with Co45Pt55 contact layers were fabricated. These diodes emit circularly-polarized light in the absence of an external magnetic field. 相似文献
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用等效介质理论计算了半无限侧向铁磁/铁磁超晶格的推迟模式.且以Co/Ni体系超晶格为例具体计算了该超晶格的表面模式和体模式,展示出一些与磁性/非磁性超晶格不同的有趣性质.侧向磁性/磁性超晶格具有较复杂的推迟模式,这是一种具有高度一般性的体系,在改变构成超晶格的两种铁磁层的厚度的比值、外场时,可以调节两支表面模式的频率以及体模式的频带,这种调节作用是与两种铁磁层的饱和磁化值有关的.当饱和磁化值相差较大时,调制效果是很明显的.当第二种铁磁介质饱和磁化值趋于零时,该体系演变成熟知的磁性/非磁性超晶格.当取麦克斯
关键词:
铁磁/铁磁超晶格
推迟模式
等效介质理论
自旋波谱 相似文献
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Sonochemical production of tin(II) and tin(IV) sulfides is investigated. Different conditions of syntheses are examined: used solvent (ethanol or ethylenediamine), source of tin (SnCl2 or SnCl4), the molar ratio of thioacetamide to the tin source, and time of sonication. The obtained powders are characterized by the X-ray diffraction method (PXRD), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX), and the Tauc method. Raman and FT-IR measurements were performed for the obtained samples, which additionally confirmed the crystallinity and phase composition of the samples. The influence of experimental conditions on composition (is it SnS or SnS2), morphology, and on the bandgap of obtained products is elucidated. It was found that longer sonication times favor more crystalline product. Each of bandgaps is direct and most of them show typical values – c.a. 1.3 eV for SnS and 2.4 eV for SnS2. However, there are some exceptions. Synthesized powders show a variety of forms such as needles, flower-like, rods, random agglomerates (SnS2) and balls (SnS). Using ethanol as a solvent led to powders of SnS2 independently of which tin chloride is used. Sonochemistry in ethylenediamine is more diverse: this solvent protects Sn2+ cations from oxidation so mostly SnS is obtained, while SnCl4 does not produce powder of SnS2 but Sn(SO4)2 instead or, at a higher ratio of thioacetamide to SnCl4, green clear mixture. 相似文献
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《Physics letters. A》2006,355(1):77-80
In this Letter, we calculate the magnetostatic modes of a semi-infinite lateral ferromagnetic/ferromagnetic superlattice with the effective-medium theory and present the general features of the modes. The numerical calculations for Co/Ni superlattice show some interesting properties which different from the lateral ferromagnetic/nonmagnetic superlattice. Two branches of the surface modes appear for the superlattice. Comparing with the surface magnetostatic modes of bulk Ni, one branch of the mode is of high frequency; the other branch of mode is of low frequency. 相似文献
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S. N. Vdovichev B. A. Gribkov S. A. Gusev E. Il’ichev A. Yu. Klimov Yu. N. Nozdrin G. L. Pakhomov V. V. Rogov R. Stolz A. A. Fraerman 《JETP Letters》2004,80(10):651-654
The effect of a system of ferromagnetic particles on the field-dependent critical current of a Josephson junction is experimentally studied for junctions of different geometries. For edge junctions, the effect of commensurability between the periodic magnetic field of the particles and the Josephson vortex lattice is observed. The effect manifests itself in additional maxima of the field-dependent critical current. For overlap junctions, giant (greater than sixfold) variations of the maximum critical current are observed depending on the magnetic state of the particles. The changes in the “Fraunhofer” pattern of the overlaped Josephson junctions are attributed to the formation of Abrikosov vortices due to the effect of uniformly magnetized particles. The effects revealed in the experiments can be used to analyze the inhomogeneous magnetic field of a system of submicron particles and to control the transport properties of Josephson junctions. 相似文献
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S.N. Vdovichev B.A. Gribkov S.A. Gusev E. Il’ichev Yu.N. Nozdrin G.L. Pakhomov A.V. Samokhvalov R. Stolz A.A. Fraerman 《Journal of magnetism and magnetic materials》2006
The effect of an array of ferromagnetic nanoparticles on the field-dependent critical current of the short overlap Josephson junction is experimentally studied. Large reversible variations of the maximum critical current are observed depending on the magnetic state of the particles. The pronounced commensurability effects are detected which are proved by the additional peaks of magnetic field induced diffraction pattern. 相似文献
9.
H. Yi J. Yu S.-I. Lee 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,7(4):509-512
To study the proposed phase separations in doped manganites, we performed Monte-Carlo calculations for the ferromagnetic Kondo
lattice model with strong Hund's coupling between conduction electrons and localized spins. For the practical calculations,
we adopted a one dimensional lattice and treated the spins of the localized t2g electrons semi-classically. A direct evidence of the phase separation is observed from a snapshot of the spatial dependence
of localized spins. No indication of the canted or spiral phases is found in the results of simulations. Further, the calculated
results of the spin structure factor in the phase separation region are well compared with recent experiments.
Received: 1st September 1998 / Revised: 30 October 1998 / Accepted: 27 November
1998 相似文献
10.
《中国物理 B》2015,(4)
We investigate the quantum transport property in gapped graphene-based ferromagnetic/normal/ferromagnetic(FG/NG/FG) junctions by using the Dirac–Bogoliubov–de Gennes equation. The graphene is fabricated on Si C and BN substrates separately, so carriers in FG/NG/FG structures are considered as massive relativistic particles. Transmission probability, charge, and spin conductances are studied as a function of exchange energy of ferromagnets(h), size of graphene gap, and thickness of normal graphene region(L) respectively. Using the experimental values of Fermi energy in the normal graphene part(EFN~ 400 me V) and energy gap in graphene(260 me V for Si C and 50 me V for BN substrate), it is shown that this structure can be used for both spin-up and spin-down polarized current. The latter case has different behavior of gapped FG/NG/FG from that of gapless FG/NG/FG structures. Also perfect charge giant magnetoresistance is observed in a range of EFN- mv2F h EFN+ mv2 F. 相似文献
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Exchange bias phenomena appear not only in ferromagnetic/antiferromagnetic systems but also in ferromagnetic/ferromagnetic systems in which two layers are nearly perpendicularly coupled. We investigated the origin of the symmetry-breaking mechanism and the relationship between the exchange bias and the system's energy parameters. We compared the results of computational Monte Carlo simulations with those of theoretical model calculation. We found that the exchange bias exhibited nonlinear behaviors, including sign reversal and singularities. These complicated behaviors were caused by two distinct magnetization processes depending on the interlayer coupling strength. The exchange bias reached a maximum at the transition between the two magnetization processes. 相似文献
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We introduce a path to a possibly new class of magnetic materials whose properties are determined entirely by the presence of a low concentration of specific point defects. Using model Hamiltonian and ab initio band structure methods we demonstrate that even large band gap nonmagnetic materials as simple as CaO with a small concentration of Ca vacancies can exhibit extraordinary properties. We show that such defects will initially bind the introduced charge carriers at neighboring sites and depending on the internal symmetry of the clusters so formed, will exhibit "local" magnetic moments which for concentrations as low as 3% transform this nonmagnetic insulator into a half-metallic ferromagnet. 相似文献
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《Current Applied Physics》2015,15(6):722-726
The electron transport through ferromagnetic/normal/ferromagnetic silicene junction with an induced energy gap is investigated in this work. The energy gap can be tuned by applying electric field or exchange fields due to the buckled structure of silicene. We analyze the local electric field, exchange field, length of normal region-dependence transmission probabilities of four groups and valley conductance. These transmission probabilities and valley conductance can be turned on or off by adjusting the local electric field and exchange field. In particular, a fully valley polarized conductance with 80% transmission is found in this junction, which can be caused by the interplay of valley-dependent massive Dirac electron, the exchange potential and the on-site potential difference of sublattices. Our findings will benefit applications in silicene-based high performance nano-electronics. 相似文献