共查询到20条相似文献,搜索用时 15 毫秒
1.
R. Huber P. Klemm S. Neusser B. Botters A. Wittmann M. Weiler S.T.B. Goennenwein C. Heyn M. Schneider P. B?ni D. Grundler 《Solid State Communications》2010,150(11-12):492-495
Spin-dependent properties of nanomagnets and magnetic/nonmagnetic hybrid systems have gained a renewed interest after the discovery of spin caloric transport phenomena. To explore such properties in detail, advanced techniques need to be developed. In this paper we report novel approaches to study both the magneto–thermal and magneto–mechanical characteristics of hybrid systems. These techniques involve in particular broadband spectroscopy of spin dynamics and surface acoustic waves in the GHz frequency regime. By these means we investigate ferromagnet/semiconductor hybrid systems to explore spin pumping and the Seebeck effect as well as ferromagnet/piezoelectric hybrid systems to address magneto–mechanical coupling at high frequencies. 相似文献
2.
In this paper, conductance of spin and electron in graphene-based ferromagnet—superconductor (FS) and parallel and antiparallel ferromagnet–superconductor–ferromagnet (FSF) junctions are studied. Using the Dirac–Bogoliubov–de Gennes equations, Andreev and normal reflections are obtained and then using these coefficients, conductance of spin and electrons are calculated at the FS interface(s) analytically. As a result, both the energy dependence of spin and charge differential conductances are investigated and a comparison between electron and spin transport is done in this paper. Effect of exchange energy of ferromagnet h on conductances is studied too. 相似文献
3.
Spin Hall Magnetoresistance and Spin Nernst Magnetothermopower in a Rashba System: Role of the Inverse Spin Galvanic Effect
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In ferromagnet/normal‐metal bilayers, the sensitivity of the spin Hall magnetoresistance and the spin Nernst magnetothermopower to the boundary conditions at the interface is of central importance. In general, such boundary conditions can be substantially affected by current‐induced spin polarizations. In order to quantify the role of the latter, we consider a Rashba two‐dimensional electron gas with a ferromagnet attached to one side of the system. The geometry of such a system maximizes the effect of current‐induced spin polarization on the boundary conditions, and the spin Hall magnetoresistance is shown to acquire a non‐trivial and asymmetric dependence on the magnetization direction of the ferromagnet. 相似文献
4.
Energy spectra of long wavelength spin wave excitations and additional low-lying spin wave excitations near the first peak in the static structure factor of an amorphous ferromagnet Co4P are calculated in the Heisenberg model. 相似文献
5.
Tunneling current in a ferromagnet/superconductor/ferromagnet double tunnel junction induces a nonequilibrium spin accumulation in the superconductor. We study theoretically the response of such a system to applied magnetic field. We show that the interplay between the magnetic field and the spin accumulation could lead to novel bias voltage dependence and magnetic field dependence of the superconducting gap function, and bring in anomalous asymmetry in the spin-dependent transport. Our study also indicates a possible application of the spin injection. 相似文献
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The problem on spectrum of linear excitations in the presence of a moving domain wall in 1D Heisenberg ferromagnet with orthorhombic anisotropy is exactly solved. The explicit expressions for spin waves scattering on the domain wall are obtained. The phase shift of a spin wave, as the result of collision of spin wave with a moving wall, is exactly determined. The change in magnon density of states is calculated from this scattering data, and the contribution of domain walls to the classical low-temperature thermodynamics is found. 相似文献
8.
S. Takahashi T. Yamashita H. Imamura S. Maekawa 《Journal of magnetism and magnetic materials》2002,240(1-3):100-102
The effect of spin relaxation on tunnel magnetoresistance (TMR) in a ferromagnet/superconductor/ferromagnet (FM/SC/FM) double tunnel junction is theoretically studied. The spin accumulation in SC is determined by balancing of the spin-injection rate and the spin-relaxation rate. In the superconducting state, the spin-relaxation time τs becomes longer with decreasing temperature, resulting in a rapid increase of TMR. The TMR of FM/SC/FM junctions provides a useful probe to extract information about spin-relaxation in superconductors. 相似文献
9.
Costache MV Sladkov M Watts SM van der Wal CH van Wees BJ 《Physical review letters》2006,97(21):216603
We report direct electrical detection of spin pumping, using a lateral normal-metal/ferromagnet/normal-metal device, where a single ferromagnet in ferromagnetic resonance pumps spin-polarized electrons into the normal metal, resulting in spin accumulation. The resulting backflow of spin current into the ferromagnet generates a dc voltage due to the spin-dependent conductivities of the ferromagnet. By comparing different contact materials (Al and/or Pt), we find, in agreement with theory, that the spin-related properties of the normal metal dictate the magnitude of the dc voltage. 相似文献
10.
《Journal of magnetism and magnetic materials》2002,253(3):111-117
Spin waves in easy-plane two-dimensional ferromagnet when anisotropy is much stronger than exchange are investigated. The spectra of magnons, the spin–spin and quadrupolar correlation functions have been derived. It is shown that in such a system there exist spin waves at low temperatures. Some properties of the quadrupolar ordering in ferromagnets are discussed. 相似文献
11.
S. Dickmann 《JETP Letters》2011,93(2):86-90
Spin relaxation in quantum Hall ferromagnet regimes is studied. As the initial non-equilibrium state, a coherent deviation
of the spin system from the B direction is considered and the breakdown of this Goldstone-mode state due to hyperfine coupling to nuclei is analyzed. The
relaxation occurring non-exponentially with time is studied in terms of annihilation processes in the “Goldstone condensate”
formed by “zero spin excitons”. The relaxation rate is calculated analytically even if the initial deviation is not small.
This relaxation channel competes with the relaxation mechanisms due to spin-orbit coupling, and at strong magnetic fields
it becomes dominating. 相似文献
12.
Electrical detection of a spin accumulation in a nondegenerate semiconductor using a tunnel barrier and ferromagnetic contact is shown to be fundamentally affected by the energy barrier associated with the depletion region. This prevents the ferromagnet from probing the spin accumulation directly, strongly suppresses the magnetoresistance in current or potentiometric detection, and introduces nonmonotonic variation of spin signals with voltage and temperature. Having no analogue in metallic systems, we identify energy mismatch as an obstacle for spin detection, necessitating control of the energy landscape of spin-tunnel contacts to semiconductors. 相似文献
13.
《Physics letters. A》2014,378(38-39):2900-2905
We study theoretically the tunneling charge conductance in ferromagnet/spin-triplet superconductor junction with the spin–orbit coupling interface. It is shown the symmetry of the conductance about the relative angle between the magnetization in ferromagnet and the d-vector in superconductor is broken due to the presence of the interfacial Rashba spin–orbit coupling. We present the conductance for various cases of the angle. For each angle, the spin-active mechanism provided by the interface is investigated. The interface effects for different spin polarization in the ferromagnet is also considered. 相似文献
14.
The Heisenberg ferromagnet with an antiferromagnetic impurity and arbitrary spin is considered. The method is suggested for constructing the ground state of such a system, the method using the Jacobi matrix technique. As an example, there has been investigated the ferromagnet with a simple cubic lattice and the matrix spin , and the impurity spin S′ = 1. The energy and wave function of the ground state are found as dependent on the system parameters. 相似文献
15.
Hertz JA Sherrington D Nieuwenhuizen TM 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》1999,60(3):R2460-R2463
A mean-field multispin interaction spin glass model is analyzed in the presence of a ferromagnetic coupling. The static and dynamical phase diagrams contain four phases (paramagnet, spin glass, ordinary ferromagnet, and glassy ferromagnet) and exhibit reentrant behavior. The glassy ferromagnet phase has anomalous dynamical properties. The results are consistent with a nonequilibrium thermodynamics that has been proposed for glasses. 相似文献
16.
A large spin current applied to a uniform ferromagnet leads to a spin-wave instability as pointed out recently. In this Letter, it is shown that such spin-wave instability is absent in a state containing a domain wall, which indicates that nucleation of magnetic domains occurs above a certain critical spin current. This scenario is supported also by an explicit energy comparison of the two states under spin current. 相似文献
17.
V. A. Malyshev 《Communications in Mathematical Physics》1975,40(1):75-82
The existence of a phase transition of the first kind is proved for anisotropic classical Heisenberg ferromagnet in two or more dimensions and with arbitrary parameter of anisotropy α, |α|<1; a similar fact is proved for much more general lattice spin systems. 相似文献
18.
The ground state of the J 1-J 2 Heisenberg model with arbitrary signs of exchange is studied for spin S = 1/2 in the case of the two-dimensional (2D) square lattice. The states with different types of spin long-range order (antiferromagnetic checkerboard, stripe, collinear ferromagnetic) as well as the disordered spin liquid states are described in the framework of one analytical approach. In particular, it is shown that the phase transition between the ferromagnetic spin liquid and the ferromagnet with long-range order is of the second order. In the vicinity of such transition, we have found the ferromagnetic state with a rapidly varying condensate function. 相似文献
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采用基于密度泛函理论(DFT)框架下的第一性原理平面波赝势(PWP)方法,结合广义梯度近似(GGA),对三元化合物ZnVSe2晶体的电子结构进行了计算,分析了ZnVSe2晶体自旋极化的能带结构、电子态密度、电荷布居、磁矩等.计算结果表明,三元化合物ZnVSe2会产生自旋极化状态,能带结构和态密度显示为半金属特征,表现出显著的铁磁性行为,具有高达近100%的传导电子自旋极化率,其半金属能隙为0.443eV,理论预测其可能是一种具有一定应用潜能
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2')" href="#">ZnVSe2
平面波赝势方法
半金属铁磁性
第一性原理 相似文献