Perfect Valley Filter in Topological Domain Wall

TL;DR

This paper introduces a topologically protected valley filter using chiral domain-wall channels between quantum anomalous Hall and quantum valley Hall insulators, achieving perfect valley polarization without backscattering.

Contribution

It presents a novel realization of perfect valley filters with topologically protected channels that are controllable and detectable via external fields and circular dichroism.

Findings

Channels are unidirectional and 100% valley-polarized.

Valley index and chirality are topologically protected.

Channels are controllable by external fields.

Abstract

We propose a realization of perfect valley filters based on the chiral domain-wall channels between a quantum anomalous Hall insulator and a quantum valley Hall insulator. Uniquely, all these channels reside in the same valley and propagate unidirectionally, $100\%$ valley-polarizing passing-by carriers without backscattering. The valley index, the chirality, and the number of the channels are protected by topological charges, controllable by external fields, and detectable by circular dichroism.