Current-induced spin polarization for a general two-dimensional electron system

In this paper, current-induced spin polarization for two-dimensional electron gas with a general spin-orbit interaction is investigated. For isotropic energy spectrum, the in-plane current-induced spin polarization is found to be dependent on the electron density for non-linear spin-orbit interaction and increases with the increment of sheet density, in contrast to the case for $\bm k$-linear spin-orbit coupling model. The numerical evaluation is performed for InAs/InSb heterojunction with spin-orbit coupling of both linear and cubic spin-orbit coupling types. For $\delta$-type short-range electron-impurity scattering, it is found that the current-induced spin polarization increases with increasing the density when cubic spin-orbit couplings are considered. However, for remote disorders, a rapid enhancement of current-induced spin polarization is always observed at high electron density, even in the case without cubic spin-orbit coupling. This result demonstrates the collision-related feature of current-induced spin polarization. The effects of different high order spin-orbit couplings on spin polarization can be comparable.