Disorder-Induced Broadening of the Density of States for 2D Electrons with Strong Spin-Orbit Coupling

TL;DR

This paper theoretically investigates how disorder and strong spin-orbit coupling affect the density of states in 2D electron systems, revealing that strong spin-orbit coupling simplifies the analysis and influences the energy distribution tail.

Contribution

It demonstrates that in the strong spin-orbit coupling limit, the coherent potential approximation becomes exact and characterizes the density of states tail using an instanton approach.

Findings

Smearing energy scale increases with spin-orbit coupling

Self-intersection diagrams are negligible at strong spin-orbit coupling

Density of states tail is characterized by a smaller energy scale

Abstract

We study theoretically the disorder-induced smearing of the density of states in a two-dimensional electron system taking into account a spin-orbit term in the Hamiltonian of a free electron. We show that the characteristic energy scale for the smearing increases with increasing the spin-orbit coupling. We also demonstrate that in the limit of a strong spin-orbit coupling the diagrams with self-intersections give a parametrically small contribution to the self-energy. As a result, the coherent potential approximation becomes asymptotically exact in this limit. The tail of the density of states has the energy scale which is much smaller than the magnitude of the smearing. We find the shape of the tail using the instanton approach.