Quantum spin/valley Hall effect and topological insulator phase transitions in silicene

TL;DR

This paper theoretically demonstrates how electric fields and spin-orbit interactions induce topological phase transitions in silicene, enabling experimental control over quantum spin and valley Hall effects.

Contribution

It introduces a method to tune silicene's topological phases via electric fields and spin-orbit coupling, revealing new quantum Hall effects.

Findings

Transition from topological insulator to trivial insulator at charge neutrality

Quenching of quantum spin Hall effect during phase transition

Emergence of quantum valley Hall effect in silicene

Abstract

We present a theoretical realization of quantum spin and quantum valley Hall effects in silicene. We show that combination of an electric field and intrinsic spin-orbit interaction leads to quantum phase transitions at the charge neutrality point. This phase transition from a two dimensional topological insulator to a trivial insulating state is accompanied by a quenching of the quantum spin Hall effect and the onset of a quantum valley Hall effect, providing a tool to experimentally tune the topological state of silicene. In contrast to graphene and other conventional topological insulators, the proposed effects in silicene are accessible to experiments.