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1.
Spin-dependent electron transport of a waveguide with Rashba spin--orbit coupling in an electromagnetic field 下载免费PDF全文
We investigate theoretically the spin-dependent electron
transport in a straight waveguide with Rashba spin--orbit coupling
(SOC) under the irradiation of a transversely polarized
electromagnetic (EM) field. Spin-dependent electron conductance and
spin polarization are calculated as functions of the emitting
energy of electrons or the strength of the EM field by adopting the mode
matching approach. It is shown that the spin polarization can be
manipulated by external parameters when the strength of Rashba
SOC is strong. Furthermore, a sharp step structure is found to exist
in the total electron conductance. These results can be understood
by the nontrivial Rashba subbands intermixing and the electron
intersubband transition when a finite-range transversely polarized
EM field irradiates a straight waveguide. 相似文献
2.
Spin Polarization and Andreev Conductance through a Diluted Magnetic Semiconductor Quantum Wire with Spin--Orbit Interaction 下载免费PDF全文
Spin-dependent Andreev reflection and spin polarization through a diluted magnetic semiconductor quantum wire coupled to normal metallic and superconductor electrodes are investigated using scattering theory. When the spin-orbit coupling is considered, more Andreev conductance steps appear at the same Fermi energy. Magnetic semiconductor quantum wire separates the spin-up and spin-down electrons. The Fermi energy, at which different- spin-state electrons begin to separate, becomes lower due to the effect of the spin-orbit interaction. The spin filter effect can be measured more easily by investigating the Andreev conductance than by investigating the normal conductance. 相似文献
3.
The spin current in a parabolically confined semiconductor
heterojunction quantum wire with Dresselhaus spin--orbit coupling is
theoretically studied by using the perturbation method. The formulae
of the elements for linear and angular spin current densities are
derived by using the recent definition for spin current based on spin
continuity equation. It is found that the spin current in this
Dresselhaus spin--orbit coupling quantum wire is antisymmetrical,
which is different from that in Rashba model due to the difference in
symmetry between these two models. Some numerical examples for the
result are also demonstrated and discussed. 相似文献
4.
We devise an approach to measure the polarization of nuclear spins via conductance measurements. Specifically, we study the combined effect of external magnetic field, nuclear spin polarization, and Rashba spin-orbit interaction on the conductance of a quantum wire. Nonequilibrium nuclear spin polarization affects the electron energy spectrum making it time dependent. Changes in the extremal points of the spectrum result in time dependence of the conductance. The conductance oscillation pattern can be used to obtain information about the amplitude of the nuclear spin polarization and extract the characteristic time scales of the nuclear spin subsystem. 相似文献
5.
We study the spin-dependent transport through a one-dimensional quantum ring with taking both the Rashba spin--orbit coupling (RSOC) and ferromagnetic leads into consideration. The linear conductance is obtained by the Green's function method. We find that due to the quantum interference effect arising from the RSOC-induced spin precession phase and the difference in travelling phase between the two arms of the ring, the conductance becomes spin-polarized even in the antiparallel magnetic configuration of the two leads, which is different from the case in single conduction channel system. The linear conductance, the spin polarization and the tunnel magnetoresistance are periodic functions of the two phases, and can be efficiently tuned by the structure parameters. 相似文献
6.
Modulation of Spin Distribution and Spin Transport by a Magnetic Field in a Quasi-One-Dimensional System with Spin--Orbit Coupling 下载免费PDF全文
The distributions of spin and currents modulated by magnetic field in a transverse parabolic confined two-dimensional electronic system with a Rashba spin--orbit coupling have been studied numerically. It is shown that the spin accumulation and the spin related current are generated by magnetic field if the spin--orbit coupling is presented. The distributions of charge and spin currents are antisymmetrical along the cross-section of confined system. A transversely applied electric field does not influence the characteristic behaviour of charge- and spin-dependent properties. 相似文献
7.
We theoretically investigate the spin transport properties of the Cooper pairs in a conventional Josephson junction with Rashba spin-orbit coupling considered in one of the superconducting leads.It is found that an angle-resolved spin supercurrent flows through the junction and a nonzero interfacial spin Hall current driven by the superconducting phase difference also appears at the interface.The physical origin of this is that the Rashba spin-orbit coupling can induce a triplet order parameter in the s-wave superconductor.The interfacial spin Hall current dependences on the system parameters are also discussed. 相似文献
8.
Z.-Y. Zhang 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(1):65-69
Along the lines of Blonder, Tinkham and Klapwijk, we investigate
the charge transport through ferromagnet/two-dimensional
electronic gas/d-wave superconductor (F/2DEG/S) junctions in the
presence of Rashba spin-orbit (SO) coupling and focus our
attention on the interplay between spin polarization and spin
precession. At zero spin polarization, the spin-mixing scattering
resulted from Rashba SO coupling decreases the zero-bias
conductance peak. Under spin polarization, spin precession
introduces novel Andreev reflection, which competes with the
effect of spin-mixing scattering. If the F layer is a half metal,
the later effect is overwhelmed by that of novel Andreev
reflection. As a result, the zero-bias conductance dip caused by
spin polarization is enhanced, and at strong Rashba SO coupling, a
split zero-bias peak is found in the gap. In an intermediate
region where the two effects are comparable with each other, the
zero-bias conductance shows a reentrant behavior as a function of
Rashba SO coupling. 相似文献
9.
Influence of spin-orbit coupling induced by in-plane external electric field on the intrinsic spin-Hall effect in a Rashba two-dimensional electron gas 下载免费PDF全文
We study theoretically the influence of spin--orbit
coupling induced by in-plane external electric field on the
intrinsic spin-Hall effect in a two-dimensional electron gas with
Rashba spin--orbit coupling. We show that, after such an influence is
taken into account, the static intrinsic spin-Hall effect can be
stabilized in a disordered Rashba two-dimensional electron gas, and
the static intrinsic spin-Hall conductivity shall exhibit some
interesting characteristics as conceived in some original
theoretical proposals. 相似文献
10.
X. B. Xiao Z. X. Chen Z. F. Liu H. L. Li W. J. Nie C. Q. Zhang G. H. Zhou 《The European Physical Journal B - Condensed Matter and Complex Systems》2014,87(1):1-6
Spin-dependent electron transport in a periodically stubbed quantum wire in the presence of Rashba spin-orbit interaction (SOI) is studied via the nonequilibrium Green’s function (GF) method combined with the Landauer-Büttiker formalism. By comparing with a straight Rashba quantum wire, the magnitude of spin conductance can be enhanced obviously. In addition, the charge and spin switching can also be found in the considered system. The mechanism of these transport properties is revealed by analyzing the total charge density and spin-polarized density distributions in the stubbed quantum wire. Furthermore, periodic spin-density islands with high polarization are also found inside the stubs, owing to the interaction between the charge density islands and the Rashba SOI-induced effective magnetic field. These interesting findings may be useful in further understanding of the transport properties of low-dimensional systems and in devising an all-electrical multifunctional spintronic device based on the proposed structure. 相似文献
11.
Zhonghui Xu Weishuai Lv Mansoor B.A. Jalil Jinsong Huang Yangwan Zhong Yuguang Chen 《Physics letters. A》2018,382(39):2868-2875
Spin transport properties in a non-uniform quantum wire (QW) in the presence of both the Rashba and Dresselhaus spin–orbit couplings (SOCs) is investigated by using the non-equilibrium Green's function (NEGF) method combined with the Landauer Büttiker formalism. It is found that such a non-uniform quantum wire exhibits considerable spin polarization in its conductance in the influence of both the Rashba and Dresselhaus SOCs, and that the two SOCs' strengths strongly affect both the magnitude and sign of the electron spin polarization. Interestingly, the Rashba and Dresselhaus SOCs play the same modulating role in the electron spin polarization. The proposed nanostructure can potentially be utilized to devise an all-electrical spintronic device. 相似文献
12.
We study a one-dimensional wire with strong Rashba and Dresselhaus spin-orbit coupling (SOC), which supports Majorana fermions when subject to a Zeeman magnetic field and in the proximity of a superconductor. Using both analytical and numerical techniques we calculate the electronic spin texture of the Majorana end states. We find that the spin polarization of these states depends on the relative magnitude of the Rashba and Dresselhaus SOC components. Moreover, we define and calculate a local "Majorana polarization" and "Majorana density" and argue that they can be used as order parameters to characterize the topological transition between the trivial system and the system exhibiting Majorana bound modes. We find that the local Majorana polarization is correlated to the transverse spin polarization, and we propose to test the presence of Majorana fermions in a 1D system by a spin-polarized density of states measurement. 相似文献
13.
B. Pal A. Chakrabarti 《The European Physical Journal B - Condensed Matter and Complex Systems》2012,85(4):1-7
We investigate theoretically the spin-dependent electron transport in a Rashba quantum wire with rough edges. The charge and spin conductances are calculated as function of the electron energy and wire length by adopting the spin-resolved lattice Green function method. For a single disordered Rashba wire, it is found that the charge conductance quantization is destroyed by the edge disorder. However, a nonzero spin conductance can be generated and its amplitude can be manipulated by varying the wire length, which is attributed to the broken structure symmetries and the spin-dependent quantum interference induced by the rough boundaries. For a large ensemble of disordered Rashba wires, the average charge conductance decreases monotonically, however, the average spin conductance increases to a maximum value and then decreases, with increasing wire length. Further study shows that the influence of the rough edges on the charge and spin conductances can be eliminated by applying a perpendicular magnetic field to the wire. In addition, a very large magnitude of the spin conductance can be achieved when the electron energy lies between the two thresholds of each pair of subbands. These findings may not only benefit to further apprehend the transport properties of the Rashba low-dimensional systems but also provide some theoretical instructions to the application of spintronics devices. 相似文献
14.
A. Phirouznia F. Ghamari 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,74(3):357-362
Non-equilibrium spin accumulation in two-dimensional domain wall (DW) in the presence of external electric field and Rashba
type spin-orbit coupling within the Boltzmann semi-classical
model is investigated. Transport and relaxation of spin polarized current in the DW is governed by spin-flip rates which are
determined by the Rashba interaction and magnetic impurities. Numerical results show that at low impurity densities and nonadiabatic
transport regimes, the Rashba interaction significantly enhances spin polarization of conduction electrons inside the DW. 相似文献
15.
The spin Hall effect in a two-dimensional electron system on honeycomb lattice with both intrinsic and Rashba spin-orbit couplings is studied numerically. Integer quantized spin Hall conductance is obtained at the zero Rashba coupling limit when electron Fermi energy lies in the energy gap created by the intrinsic spin-orbit coupling, in agreement with recent theoretical prediction. While nonzero Rashba coupling destroys electron spin conservation, the spin Hall conductance is found to remain near the quantized value, being insensitive to disorder scattering, until the energy gap collapses with increasing the Rashba coupling. We further show that the charge transport through counterpropagating spin-polarized edge channels is well quantized, which is associated with a topological invariant of the system. 相似文献
16.
A generalized finite element formulation is proposed for the study of the spin-dependent ballistic transport of electron through the two-dimensional quantum structures with Rashba spin-orbit interactions (SOI). Thetransmission coefficient, conductance, the total and local polarization are numerically calculated and discussed as the Rashba coefficient, the geometric sizes, and incident energy are changed in the T-shaped devices. Some interesting features are found in the proper parameter regime. The polarization has an enhancement as the Rashba coefficient becomes stronger. The polarization valley is rigid in the regime of the conductance plateaus since the local interference among the polarized multi-wave modes. The Rashba interactions coupling to geometry in sizes could form the structure-induced Fano-Rashba resonance. In the wider stub, the localized spin lattice of electron could be produced. The conductance plateaus correspond to weakpolarizations. Strong polarizations appear when the stub sizes, incident energy, and the Rashba coupling coefficient are matched. The resonances are formed in a wide Fermi energy segment easily. 相似文献
17.
Intrinsic Hall effect and separation of Rashba and Dresselhaus spin splittings in semiconductor quantum wells 下载免费PDF全文
We have proposed a method to separate Rashba and Dresselhaus spin splittings in
semiconductor quantum wells by using the intrinsic Hall effect. It is shown that the
interference between Rashba and Dresselhaus terms can deflect the electrons in
opposite transverse directions with a change of sign in the macroscopic Hall
current, thus providing an alternative way to determine the different contributions
to the spin--orbit coupling. 相似文献
18.
理论上研究了含stubs的Rashba自旋轨道耦合(spin-orbit coupling, SOC)量子波导系统的自旋极化输运性质. 利用晶格格林函数方法,发现由于stubs和SOC产生的势阱使系统中出现束缚态,这些束缚态与传播态之间相互干涉导致电导中出现Fano共振结构,同时在对应的自旋极化率中也出现Fano共振或反共振结构. 此外,由于系统结构的突变使电子被反向散射和量子干涉效应,电导中出现一系列的共振峰. 但是,当系统加上外磁场后,所有这些效应都被抑制, 系统重新出现量子化电导, 同时自旋电导也出
关键词:
量子波导
自旋极化输运
自旋轨道耦合 相似文献
19.
Thorsten Arnold Chi-Shung Tang Andrei Manolescu Vidar Gudmundsson 《The European Physical Journal B - Condensed Matter and Complex Systems》2014,87(5):1-20
We calculate the persistent charge and spin polarization current inside a finite-width quantum ring of realistic geometry as a function of the strength of the Rashba or Dresselhaus spin-orbit interaction. The time evolution in the transient regime of the two-dimensional (2D) quantum ring connected to electrically biased semi-infinite leads is governed by a time-convolutionless non-Markovian generalized master equation. The electrons are correlated via Coulomb interaction. In addition, the ring is embedded in a photon cavity with a single mode of linearly polarized photon field, which is polarized either perpendicular or parallel to the charge transport direction. To analyze carefully the physical effects, we compare to the analytical results of the toy model of a one-dimensional (1D) ring of non-interacting electrons with spin-orbit coupling. We find a pronounced charge current dip associated with many-electron level crossings at the Aharonov-Casher phase ΔΦ = π, which can be disguised by linearly polarized light. Qualitative agreement is found for the spin polarization currents of the 1D and 2D ring. Quantitatively, however, the spin polarization currents are weaker in the more realistic 2D ring, especially for weak spin-orbit interaction, but can be considerably enhanced with the aid of a linearly polarized electromagnetic field. Specific spin polarization current symmetries relating the Dresselhaus spin-orbit interaction case to the Rashba one are found to hold for the 2D ring, which is embedded in the photon cavity. 相似文献
20.
C. M. Wang M. Q. Pang 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,74(1):19-25
Out-of-plane spin and charge responses to the terahertz
field for a clean two-dimensional electron gas with a Rashba
spin-orbit interaction in the presence of an in-plane magnetic field
are studied. We show that the characteristic optical spectral
behavior is remarkably different from that of the system in the
absence of in-plane magnetic fields. It is found that the optical
spin polarization normal to the plane is nonzero even for this clean
system, in sharp contrast to the static case. Due to the combined
effect of spin-orbit coupling and in-plane magnetic field, both
diagonal and off-diagonal components of optical charge conductivity
tensor are nonvanishing. It is indicated that one can control the
spin polarization and the optical current by adjusting the optical
frequency. In addition, the out-of-plane spin polarization and
conductivities strongly rely on the direction of the external
magnetic field. Nevertheless, they meet different angle-dependent
relations. This dynamical out-of-plane spin polarization could be
measured by the time-resolved Kerr rotation technique. 相似文献