Spin accumulation in a ballistic Rashba bar

The intrinsic spin polarization effect in a ballistic Rashba bar with two semi-infinite leads is studied by solving continuous Schrodinger equations. The wave functions expanded with plane waves in the Rashba bar are required to satisfy boundary conditions at both longitudinal and transverse interfaces. We find that the out-of-plane spin Hall accumulation effect can be induced in the Rashba bar by injecting unpolarized current from the lead. We also observe obvious longitudinal in-plane spin Hall effect. An interesting direction flipping of the out-of-plane spin accumulation is predicted by altering the Rashba coupling strength. The symmetric relations of spin polarization under opposite biases and Rashba coupling in the ballistic region are also investigated in detail.