Anomalous magneto-optical response and chiral interface of dipolar excitons at twisted valleys

TL;DR

This paper reports the discovery of an anomalous magneto-optical response in twisted TMDs, revealing chiral exciton dispersions and strain-induced control of exciton flow, with potential for optoelectronic applications.

Contribution

It uncovers a novel magneto-optical phenomenon in dipolar valley excitons and demonstrates strain as an alternative means to induce chiral dispersions and control exciton flow.

Findings

Magneto-optical spectrum shows multiplet splitting of exciton states.

Chiral dispersions enable unidirectional exciton current injection.

Strain can replace magnetic field to induce similar effects.

Abstract

An anomalous magneto-optical spectrum is discovered for dipolar valley excitons in twisted double layer transition metal dichalcogenides (TMD), where in-plane magnetic field induces a sizable multiplet splitting of exciton states inside the light cone. Chiral dispersions of the split branches make possible efficient optical injection of unidirectional exciton current. We also find an analog effect with a modest heterostrain replacing the magnetic field for introducing large splitting and chiral dispersions in the light cone. Angular orientation of photo-injected exciton flow can be controlled by strain, with left-right unidirectionality selected by circular polarisation.