Spin-dependent electron transport of a waveguide with Rashba spin-orbit coupling in an electromagnetic field

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 he understood by the nontrivial Rashba subbands intermixing and the electron intersubband transition when a finite-range transversely polarized EM field irradiates a straight waveguide.

Polarized spin transport in mesoscopic quantum rings with electron phonon and Rashba spin-orbit coupling

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 positionsl 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.

Current-induced nonequilibrium spin polarization in semiconductor-nanowire/s-wave superconductor junctions with strong spin–orbit coupling

We have studied the characteristics of current-induced nonequilibrium spin polarization in semiconductor-nanowire/swave superconductor junctions with strong spin–orbit coupling. It was found that within some parameter regions the magnitude of the current-induced nonequilibrium spin polarization density in such structures will increase（or decrease） with the decrease（or increase） of the charge current density, in contrast to that found in normal spin–orbit coupled semiconductor structures. It was also found that the unusual characteristics of the current-induced nonequilibrium spin polarization in such structures can be well explained by the effect of the Andreev reflection.

Spontaneous Spin Polarization of Electrons by Diluted Magnetic Heterostructures

The spin dependent electron transmission phenomenon in a diluted resonant semiconductor heterostructure is employed theoretically to investigate the output transmission current polarization at zero magnetic field. Transparency of electron transmission is calculated as a function of electron energy and the well width, within the one electron band approximation along with the spin orbit interaction. Enhanced spin-polarized resonant tunneling in the heterostructure due to Dresselhaus and Rashba spin-orbit coupling induced splitting of the resonant level is observed. We predict that a spin-polarized current spontaneously emerges in this heterostructure and we estimate theoretically that the polarization can reach 40%. This effect could be employed in the fabrication of spin filters, spin injectors and detectors based on non-magnetic semiconductors.

Precision mapping the topological bands of 2D spin-orbit coupling with microwave spin-injection spectroscopy

To investigate the band structure is one of the key approaches to study the fundamental properties of a novel material.We report here the precision band mapping of a 2-dimensional(2D) spin-orbit(SO) coupling in an optical lattice.By applying the microwave spin-injection spectroscopy, the band structure and spin-polarization distribution are achieved simultaneously.The band topology is also addressed with observing the band gap close and re-open at the Dirac points.Furthermore, the lattice depth and the Raman coupling strength are precisely calibrated with relative errors in the order of 10^(-3).Our approach could also be applied for exploring the exotic topological phases with even higher dimensional system.

Thermoelectric response of spin polarization in Rashba spintronic systems

Motivated by the recent discovery of a strongly spin-orbit-coupled two-dimensional （2D） electron gas near the surface of Rashba semiconductors BiTeX （X = Cl, Br, I）, we calculate the thermoelectric responses of spin polarization in a 2D Rashba model. By self-consistently determining the energy- and band-dependent transport time, we present tion for elastic scattering. Using this solution, an exact solution of the linearized Boltzmann equa- we find a non-Edelstein electric-field-induced spin polarization that is linear in the Fermi energy EF when EF lies below the band crossing point. The spin polarization efficiency, which is the electric-field-induced spin polarization divided by the driven electric current, increases for smaller EF. We show that, as a function of EF, the temperature- gradient-induced spin polarization increases continuously to a saturation value when EF decreases below the band crossing point. As the temperature tends to zero, the temperature-gradient-induced spin polarization vanishes.

Progress of hidden spin polarization in inversion-symmetric crystals

Hidden spin polarization refers to that doubly degenerate bands protected by combined inversion and time-reversal symmetry in nonmagnetic inversion-symmetric crystals could have opposite non-zero local spin polarizations, which are spatially separated in two real-space sectors paired by the inversion symmetry. Since its first prediction from ab initio calculation, hidden spin polarization has inspired tremendous interest and has been observed experimentally due to its intriguing fundamental properties as well as the great potential for applications. Moving forward, the search for moment-dependent spin splitting has also been extended to antiferromagnets even without considering spin-orbit coupling. This paper systematically reviews recent works in this field with a focus on basic concepts and material realization. It also details several remaining bottlenecks and suggests possible avenues for future research.

The kinetic magnetoelectric effect in laterally boundary-confined ballistic two-dimensional hole gases

A theoretical investigation is presented on the characteristics of the kinetic magnetoelectric effect in laterally boundary-confined ballistic two-dimensional hole gases. It was shown that, though the momentum-dependent effective magnetic fields felt by charge carriers due to the spin-orbit interaction are in-plane orientated in such systems, both in-plane polarized and normal polarized nonequilibrium spin polarization densities could be electrically induced by the kinetic magnetoelectric effect, and the induced nonequilibrium spin polarizations exhibit some interesting characteristics. The characteristics we found indicate that there may be some possible relation between this effect and some recent experimental findings.

含stubs量子波导系统的电子自旋极化输运性质

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,同时自旋电导也出现台阶结构.其物理根源是因为磁场相当于增加了一个横向限制势而使子带间的干涉效应变弱.