Quantum percolation in quantum spin Hall antidot systems

TL;DR

This paper investigates how antidot-induced bound states affect transport in quantum spin Hall insulators, revealing that at critical densities, these states can destroy the topological phase through quantum percolation.

Contribution

It introduces the concept of quantum percolation induced by antidot-bound states in quantum spin Hall systems and draws analogies with quantum Hall network models.

Findings

Bound states induce quantum percolation in the insulating bulk.

Critical antidot density destroys the quantum spin Hall phase.

Intermediate extended states emerge at maximum percolation.

Abstract

We study the influences of antidot-induced bound states on transport properties of two- dimensional quantum spin Hall insulators. The bound statesare found able to induce quantum percolation in the originally insulating bulk. At some critical antidot densities, the quantum spin Hall phase can be completely destroyed due to the maximum quantum percolation. For systems with periodic boundaries, the maximum quantum percolationbetween the bound states creates intermediate extended states in the bulk which is originally gapped and insulating. The antidot in- duced bound states plays the same role as the magnetic field inthe quantum Hall effect, both makes electrons go into cyclotron motions. We also draw an analogy between the quantum percolation phenomena in this system and that in the network models of quantum Hall effect.