‘‘Spin’’ splitting in asymmetric double quantum wells: A mechanism for ‘‘spin’’-dependent hole delocalization

Abstract

We show how the breakdown of Kramers degeneracy for spin-orbit coupled bands in asymmetric double quantum wells may give rise to a new mechanism for tunneling which does not require resonant conditions. The most interesting aspect of this finding is that, in this case, there is a ``spin''-dependent delocalization of the wave function, leading to preferential tunneling of one ``spin'' state. We relate this effect to the symmetry properties of the wave functions of both single and asymmetric double quantum wells, and provide a qualitative explanation in terms of perturbation theory.