Level statistics in a two-dimensional system with strong spin-orbit coupling

Abstract

We study level correlations in a two-dimensional system with a long-range random potential and strong spin-orbit (SO) splitting of the spectrum. The level correlations for sufficiently large splitting are shown to be described by orthogonal Wigner-Dyson statistics, in contrast to the common point of view that a system with the strong SO coupling belongs to the symplectic statistical ensemble. We demonstrate also that in a wide energy interval the level statistics is completely determined by transitions between two branches of the split spectrum. A sharp resonance is obtained in the two-level correlation function at energy equal to the value of SO splitting.