Spin-orbit interaction in symmetric wells and cycloidal orbits without magnetic fields

Abstract

We investigate the spin-orbit (s-o) interaction in two-dimensional electron gases (2DEGs) in quantum wells with two subbands. From the Kane model, we derive a new inter-subband-induced s-o coupling which resembles the functional form of the Rashba s-o -- but is non-zero even in structures. This follows from the distinct parity of the confined states (even/odd) which obliterates the need for asymmetric potentials. Interestingly, our s-o interaction gives rise to an unusual of spin-polarized electrons with cycloidal trajectories magnetic fields. We also predict a sizable effective-mass renormalization due to the s-o--induced subband warping.