Interface states in two-dimensional electron systems with spin-orbital interaction

TL;DR

This paper investigates interface states in 2D electron systems with spin-orbit interaction, revealing their unexpected existence, sensitivity to interfacial potentials, and unique size quantization behavior.

Contribution

It introduces a theoretical analysis of interface states with generalized boundary conditions, highlighting their existence without potential barriers and their complex energy spectrum.

Findings

Interface states can exist even with zero effective interface potential.

The energy of interface states can lie in both forbidden and conduction bands.

Size quantization energy shows a non-monotonic dependence on strip width.

Abstract

Interface states at a boundary between regions with different spin-orbit interactions (SOIs) in two-dimensional (2D) electron systems are investigated within the one-band effective mass method with generalized boundary conditions for envelope functions. We have found that the interface states unexpectedly exist even if the effective interface potential equals zero. Depending on the system parameters, the energy of these states can lie in either or both forbidden and conduction bands of bulk states. The interface states have chiral spin texture similar to that of the edge states in 2D topological insulators. However, their energy spectrum is more sensitive to the interfacial potential, the largest effect being produced by the spin-dependent component of the interfacial potential. We have also studied the size quantization of the interface states in a strip of 2D electron gas with SOI and found an unusual (non-monotonic) dependence of the quantization energy on the strip width.