Valley-Polarized Quantum Anomalous-Hall Effects in Silicene

TL;DR

This paper reports the discovery of a valley-polarized quantum anomalous Hall state in monolayer silicene, achieved by tuning Rashba spin-orbit coupling, revealing a new topological phase with combined valley and Hall effects.

Contribution

It introduces a novel valley-polarized quantum anomalous Hall state in silicene, demonstrating a tunable topological phase transition driven by Rashba spin-orbit coupling.

Findings

Realization of a C=2 quantum anomalous Hall state in silicene.

Identification of a topological phase transition induced by Rashba coupling.

Observation of a state with combined quantum valley-Hall and anomalous Hall properties.

Abstract

We demonstrate a new quantum state of matter---valley-polarized quantum anomalous Hall effect in monolayer silicene. In the presence of extrinsic Rashba spin-orbit coupling and exchange field, monolayer silicene can host a quantum anomalous-Hall state with Chern number C=2. We find that through tuning Rashba spin-orbit coupling, a topological phase transition gives rise to a valley polarized quantum anomalous Hall state, i.e. a quantum state which exhibits electronic properties of both quantum valley-Hall effect (valley Chern number C_V=3) and quantum anomalous Hall effect with C=-1.