Optically Probing Tunable Band Topology in Atomic Monolayers

TL;DR

This paper demonstrates how optical methods can be used to probe and control the topological properties of electronic bands in atomic monolayers, revealing tunable band topology through excitonic transitions.

Contribution

It introduces a method to optically detect and manipulate band topology in monolayers via gate-controlled changes in valley winding and excitonic transitions.

Findings

Optical selection rules are influenced by band topology near valleys.

Gate control can tune band ordering and valley winding number.

First-principles calculations suggest realization in Sb-based monolayers.

Abstract

In many atomically thin materials their optical absorption is dominated by excitonic transitions. It was recently found that optical selection rules in these materials are influenced by the band topology near the valleys. We propose that gate-controlled band ordering in a single atomic monolayer, through changes in the valley winding number and excitonic transitions, can be probed in helicity-resolved absorption and photoluminescence. This predicted tunable band topology is confirmed by combining an effective Hamiltonian and a Bethe-Salpeter equation for an accurate description of excitons, with first-principles calculations suggesting its realization in Sb-based monolayers.