Spin polarization direction switch based on an asymmetrical quantum wire

A scheme for a spin polarization direction switch is investigated by studying the spin-dependent electron transport of an asymmetrical quantum wire with Rashba spin–orbit coupling. It is found that the spin polarization direction can be switched by changing the direction of the external current. The physical mechanism of this device arises from the fact that the symmetries in the longitudinal and transverse directions are all broken but _C2$C_2$-rotation and time-reversal symmetries are still preserved. Further studies show that the spin polarization is robust against disorder, displaying the feasibility of the proposed structure for a potential application.