Robust AC Quantum Spin Hall Effect without Participation of Edge States

TL;DR

This paper introduces the concept of an AC quantum spin Hall effect that occurs in the bulk, independent of edge states, offering a more robust platform for AC spintronics applications in topological insulators.

Contribution

It demonstrates that the AC QSH effect can exist without edge states, differing from the traditional DC QSH effect, and is resilient to symmetry breaking and disorder.

Findings

AC QSH effect occurs in the bulk without edge states

The effect is robust against time-reversal symmetry breaking

Potential for practical AC spintronics applications

Abstract

The quantum spin Hall (QSH) effect in the DC regime, which has been intensively researched, relies on the existence of symmetry-protected edge states. Here, we demonstrate that a QSH system behaves quite differently in response to an applied AC electric field, and put forward the idea of AC QSH effect. The AC QSH effect can occur in the bulk without involving the fragile edge states, hence being robust against time-reversal symmetry breaking and disorder. It lays a more solid foundation for practical applications of the two-dimensional topological insulators, in the emerging field of AC spintronics.