共查询到20条相似文献,搜索用时 0 毫秒
1.
Field-assisted electron transport through a symmetric double-well structure with spin--orbit coupling and the Fano-resonance induced spin filtering 下载免费PDF全文
We have investigated theoretically the field-driven electron-transport through a double-quantum-well semiconductor-heterostructure with spin-orbit coupling. The numerical results demonstrate that the transmission spectra are divided into two sets due to the bound-state level-splitting and each set contains two asymmetric resonance peaks which may be selectively suppressed by changing the difference in phase between two driving fields. When the phase difference changes from 0 to π, the dip of asymmetric resonance shifts from one side of resonance peak to the other side and the asymmetric Fano resonance degenerates into the symmetric Breit-Wigner resonance at a critical value of phase difference. Within a given range of incident electron energy, the spin polarization of transmission current is completely governed by the phase difference which may be used to realize the tunable spin filtering. 相似文献
2.
Field-assisted spin-polarized electron transport through a single quantum well with spin-orbit coupling 下载免费PDF全文
We have investigated theoretically the field-driven electron transport through a single-quantum-well semiconductor heterostructure with spin-orbit coupling.The splitting of the asymmetric Fano-type resonance peaks due to the Dresselhaus spin-orbit coupling is found to be highly sensitive to the direction of the incident electron.The splitting of the Fano-type resonance induces the spin-polarization dependent electron current.The location and the line shape of the Fano-type resonance can be controlled by adjusting the energy and the direction of the incident electron,the oscillation frequency,and the amplitude of the external field.These interesting features may be used to devise tunable spin filters and realize pure spin transmission currents. 相似文献
3.
Field-assisted spin-polarized electron transport through a single quantum well with spinben orbit coupling 下载免费PDF全文
We have investigated theoretically the field-driven electron transport through a single-quantum-well semiconductor heterostructure with spin-orbit coupling. The splitting of the asymmetric Fano-type resonance peaks due to the Dresselhaus spin-orbit coupling is found to be highly sensitive to the direction of the incident electron. The splitting of the Fano-type resonance induces the spin-polarization dependent electron current. The location and the line shape of the Fano-type resonance can be controlled by adjusting the energy and the direction of the incident electron, the oscillation frequency, and the amplitude of the external field. These interesting features may be used to devise tunable spin filters and realize pure spin transmission currents. 相似文献
4.
5.
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
6.
Polarized spin transport in mesoscopic quantum rings with electron--phonon and Rashba spin--orbit coupling 下载免费PDF全文
The influence of electron--phonon (EP) scattering on spin
polarization of current output from a mesoscopic ring with Rashba
spin--orbit (SO) interaction is numerically investigated. There are
three leads connecting to the ring at different positions;
unpolarized current is injected to one of them, and the other two
are output channels with different bias voltages. The spin
polarization of current in the outgoing leads shows oscillations as a
function of EP coupling strength owing to the quantum interference
of EP states in the ring region. As temperature increases, the
oscillations are evidently suppressed, implying decoherence of
the EP states. The simulation shows that the magnitude of polarized
current is sensitive to the location of the lead. The polarized
current depends on the connecting position of the lead in a
complicated way due to the spin-sensitive quantum interference
effects caused by different phases accumulated by transmitting
electrons with opposite spin states along different paths. 相似文献
7.
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
8.
Electron transport for a laser-irradiated quantum channel with Rashba spin--orbit coupling 下载免费PDF全文
We investigate theoretically the electron transport for a two-level
quantum channel (wire) with Rashba spin--orbit coupling under the
irradiation of a longitudinally-polarized external laser field at low
temperatures. Using the method of equation of motion for Keldysh
nonequilibrium Green function, we examine the time-averaged spin
polarized conductance for the system with photon polarization
parallel to the wire direction. By analytical analysis and a few
numerical examples, the interplay effects of the external laser field
and the Rashba spin--orbit coupling on the spin-polarized conductance
for the system are demonstrated and discussed. It is found that the
longitudinally-polarized laser field can adjust the spin polarization
rate and produce some photon sideband resonances of the conductance
for the system. 相似文献
9.
Spin-dependent Breit-Wigner and Fano resonances in photon-assisted electron transport through a semiconductor heterostructure 下载免费PDF全文
We theoretically investigate the electron transmission through a seven-layer semiconductor heterostructure with the Dresselhaus spin-orbit coupling under two applied oscillating fields. Numerical results show that both of the spin-dependent symmetric Breit-Wigner and the asymmetric Fano resonances appear and that the properties of these two types of resonance peaks are dependent on the amplitude and the relative phases of the two applied oscillating fields. The modulation of the spin-polarization efficiency of transmitted electrons by the relative phase is also discussed. 相似文献
10.
The influence of the Dresselhaus spin--orbit coupling on the tunnelling magnetoresistance in ferromagnet/ insulator /semiconductor/ insulator /ferromagnet tunnel junctions 下载免费PDF全文
This paper investigates the effect of Dresselhaus spin--orbit
coupling on the spin-transport properties of
ferromagnet/insulator/semiconductor/insulator/ferromagnet
double-barrier structures. The influence of the thickness of the
insulator between the ferromagnet and the semiconductor on the
polarization is also considered. The obtained results indicate that
(i) the polarization can be enhanced by reducing the insulator
layers at zero temperature, and (ii) the tunnelling magnetoresistance
inversion can be illustrated by the influence of the Dresselhaus
spin--orbit coupling effect in the double-barrier structure. Due to
the Dresselhaus spin--orbit coupling effect, the tunnelling
magnetoresistance inversion occurs when the energy of a localized
state in the barrier matches the Fermi energy EF of the
ferromagnetic electrodes. 相似文献
11.
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
12.
在Su-Schrieffer-Heeger (SSH)原子链中,电子在胞内和胞间的跳跃依赖于其自旋时,即SSH原子链存在自旋轨道耦合作用时,存在不同缠绕数的非平庸拓扑边缘态.如何探测自旋轨道耦合SSH原子链不同缠绕数的边缘态是一个重要问题.本文在紧束缚近似下研究了自旋轨道耦合SSH原子链的非平庸拓扑边缘态性质及其零能附近的电子输运特性.研究发现四重和二重简并边缘态的缠绕数分别为2和1;并且仅当源极入射电子的自旋被极化(铁磁电极)时,自旋轨道耦合SSH原子链在零能附近的电子输运特性才能反映其边缘态的能谱特性.尤其是,随着自旋轨道耦合SSH原子链与左、右导线之间的耦合强度由弱到强改变,对于缠绕数为2的四重简并边缘态,入射电子在零能附近的透射峰数目将从4个变为0;而对于缠绕数为1的二重简并边缘态情形,其透射峰数目将从2个变为0.因此,在源极为铁磁电极的情形下,通过观察自旋轨道耦合SSH原子链在零能附近电子共振透射峰的数目随着其与左、右导线之间耦合强度的变化,来探测其不同缠绕数的边缘态.上述结果为基于电子输运特性探测自旋轨道耦合SSH原子链不同拓扑性质的边缘态提供了一种可选择的理论方案. 相似文献
13.
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
14.
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
15.
Electron transport properties of an ideal one-dimensional (1D) quantum wire are studied including spatially periodic Rashba spin–orbit coupling (SOC) and Dresselhaus SOC. By comparing with the previous work [S.J. Gong, Z.Q. Yang, J. Phys. Condens. Matter 19 (2007) 446209], two transmission gaps appear in the transmission probability of electrons and their widths are also broadened dramatically. Moreover, it is found that their widths are sensitive not only to the strength of SOCs but also to the length ratio of SOCs segment and non-SOCs segment. In addition, a ‘circle-type’ transmission behavior has been found by tuning the strength of SOCs continuously. Our results may extend the previous work and provide an more effective method to manipulate the current in nanoelectric devices. 相似文献
16.
Based on the Green’s function technique and the equation of motion approach,this paper theoretically studies the thermoelectric effect in parallel coupled double quantum dots (DQDs),in which Rashba spin-orbit interaction is taken into account.Rashba spin-orbit interaction contributions,even in a magnetic field,are exhibited obviously in the double quantum dots system for the thermoelectric effect.The periodic oscillation of thermopower can be controlled by tunning the Rashba spin-orbit interaction induced phase.The interesting spin-dependent thermoelectric effects will arise which has important influence on thermoelectric properties of the studied system. 相似文献
17.
The influence of parameters such as the strength and
frequency of a periodic driving force on the tunneling dynamics is
investigated in a symmetric triple-well potential. It is shown that
for some special values of the parameters, tunneling could be
enhanced considerably or suppressed completely. Quantum fluctuation
during the tunneling is discussed as well and the numerical results
are presented and analysed by virtue of Floquet formalism. 相似文献
18.
A quantum pumping protocol through which the quasiparticles of Weyl/multi-Weyl and nodal-line semimetals are subjected to a time-periodic rectangular potential well is considered. The presence of an oscillating potential of frequency ω creates equispaced Floquet side-bands with spacing . As a result, a Fano resonance is observed when the difference in the Fermi energy (i.e., the energy of the incident quasiparticle), and the energy of one of the (quasi)bound state levels of the well, coincides with the energy of an integer number of photons (each carrying energy quantum ). Using the Floquet theory and the scattering matrix approach in the zero-temperature non-adiabatic pumping limit, characteristic Fano resonance patterns are found in the transmission coefficients. The inflection points in the pumped shot noise spectra also serve as a proxy for the corresponding Fano resonances. Therefore, the pumped shot noise is also numerically evaluated. Finally, the existence of the Fano resonance points is correlated to the (quasi)bound states of the well, by explicitly calculating the bound states of the static well (which are a subset of the bound states of the driven system). Since semimetals with anisotropic dispersions are considered, all the features observed depend on the orientation of the potential well. 相似文献
19.
Dispersive Properties of tunnelling—induced transparency in an asymmetric double quantum well 下载免费PDF全文
We have investigated the dispersive properties of tunnelling-induced transparency in asymmetric double quantum well structures where two excited states are coupled by resonant tunnelling through a thin barrier in a three-level system of electronic subbands. The intersubband transitions exhibit high dispersion at zero absorption, which leads to the slow light velocity in this medium as compared with that in vacuum (c=3×108). The group velocity in a specific GaAs/AlGaAs sample is calculated to be vg=c/4.30. This structure can be used to compensate for the dispersion and energy loss in fibre optical communications. 相似文献
20.
Fano resonance and wave transmission through a chain structure with an isolated ring composed of defects 下载免费PDF全文
We consider a discrete model that describes a linear chain of particles coupled to an isolated ring composed of N defects.This simple system can be regarded as a generalization of the familiar Fano-Anderson model.It can be used to model discrete networks of coupled defect modes in photonic crystals and simple waveguide arrays in two-dimensional lattices.The analytical result of the transmission coefficient is obtained,along with the conditions for perfect reflections and transmissions due to either destructive or constructive interferences.Using a simple example,we further investigate the relationship between the resonant frequencies and the number of defects N,and study how to affect the numbers of perfect reflections and transmissions.In addition,we demonstrate how these resonance transmissions and refections can be tuned by one nonlinear defect of the network that possesses a nonlinear Kerr-like response. 相似文献