Huai-Bing Zhuang

Bio: Huai-Bing Zhuang is an academic researcher. The author has contributed to research in topics: Spin magnetic moment & Quantum spin Hall effect. The author has an hindex of 1, co-authored 1 publications receiving 8 citations.

Edge Spin Current and Spin Polarization in Quantum Hall Regime

Abstract: We study the edge spin current and spin polarization in a two-dimensional electron gas with spin-orbit coupling in the presence of a perpendicular magnetic field. The edge effect removes the degeneracy of Landau levels due to the competition between the Rashba coupling and the Zeeman splitting, which exists in the bulk. Large spin edge current and non-linear response to an electric field are found when the two levels are degenerated in the bulk. It is found that he spin current is proportional to spin polarization along the y-direction in an finite magnetic field, which provides a way to extract the spin current in the system.

Influence of dephasing on the quantum Hall effect and the spin Hall effect

Abstract: We study the influence of the phase relaxation process on Hall resistance and spin Hall current of a mesoscopic two-dimensional four-terminal Hall cross bar with or without Rashba spin-orbit interaction (SOI) in a perpendicular uniform magnetic field. We find that the plateaus of the Hall resistance with even number of edge states can survive for very strong phase relaxation when the system size is much longer than the phase coherence length. On the other hand, the odd integer Hall resistance plateaus arising from the SOI are easily destroyed by the weak phase relaxation during the competition between the magnetic field and the SOI which delocalize the edge states. In addition, we have also studied the transverse spin Hall current and found that it exhibits resonant behavior whenever the Fermi level crosses the Landau band of the system. The phase relaxation process weakens the resonant spin Hall current and enhances the nonresonant spin Hall current.

Electric-field-induced resonant spin polarization in a two-dimensional electron gas

Abstract: Electric response of spin polarization in two-dimensional electron gas with structural inversion asymmetry subjected to a magnetic field was studied by means of the linear and non-linear theory and numerical simulation with the disorder effect. It was found by Kubo linear reponse theory that an electric resonant response of spin polarization occurs when the Fermi surface is located near the crossing of two Landau levels, which is induced from the competition between the spin-orbit coupling and Zeeman splitting. The scaling behavior was investigated with a simplified two-level model by non-linear method, and the resonant peak value is reciprocally proportional to the electric field at low temperatures and to temperature for finite electric fields. Finally numerical simulation illustrated that impurity potential opens an enegy gap near the resonant point and suppresses the effect gradually with the increasing strength of disorder. This resonant effect may provide an efficient way to control spin polarization by an external electric field.

Theory of resonant spin hall effect

Abstract: A brief review is presented on the resonant spin Hall effect, where a tiny external electric field induces a saturated spin Hall current in a 2-dimensional electron or hole gas in a perpendicular magnetic field. The phenomenon is attributed to the energy level crossing associated with the spin-orbit coupling and the Zeeman splitting. We summarize recent theoretical development of the effect in various systems and discuss possible experiments to observe the effect.

Theory of resonant spin Hall effect

Abstract: A biref review is presented on resonant spin Hall effect, where a tiny external electric field induces a saturated spin Hall current in a 2-dimensional electron or hole gas in a perpendicular magnetic field. The phenomenon is attributted to the energy level crossing associated with the spin-orbit coupling and the Zeeman splitting. We summarize recent theoretical development of the effect in various systems and discuss possible experiments to observe the effect.

In-plane electric field effect on a spin-orbit coupled two-dimensional electron system in presence of magnetic field

Abstract: The effect of in-plane electric field on Landau level spacing, spin splitting energy, average spin polarization, and average spin current in the bulk as well as at the edges of a two-dimensional electron system with Rashba spin-orbit coupling are presented here. The spin splitting energy for a particular magnetic field is found to be reduced by the external in-plane electric field. Unlike the case of a two-dimensional electron system without Rashba spin-orbit interaction, here the Landau level spacing is electric field dependent. This dependency becomes stronger at the edges in comparison to the bulk. The average spin polarization vector rotates anti-clockwise with the increase of electric field. The average spin current also gets influenced significantly by the application of the in-plane electric field.