Influence of evanescent waves on spin polarization in a ballistic Rashba bar

The influence of evanescent waves on spin polarization in a ballistic Rashba bar is investigated by solving continuous Schrodinger equations based on the expansion of evanescent waves as well as plane ones. We find that the pure evanescent waves can lead to obvious variations of spin polarization near the interfaces up to a range of several hundred nanometers. Both the range and strength of the variations are found to be strongly dependent on the incident energy. Due to the coupling between the evanescent waves and plane waves, and other factors, the influence of evanescent waves possesses long range behavior. The effects of evanescent waves on spin current and the possible relationship between spin current and polarization are also studied.