All-optical injection of charge, spin and valley currents in monolayer transition metal dichalcogenides

TL;DR

This paper proposes an all-optical method to inject charge, spin, and valley polarized currents in monolayer transition metal dichalcogenides using quantum interference effects between one- and two-photon absorption processes, enabling dynamic control.

Contribution

It introduces a novel all-optical technique for injecting polarized currents in monolayer TMDs, surpassing static field methods by exploiting nonlinear quantum interference effects.

Findings

Injected currents can be controlled via incident light parameters.

The method enables simultaneous injection of charge, spin, and valley currents.

Conditions for experimental realization are discussed.

Abstract

Monolayer transition metal dichalcogenides have recently become a playground for spin- and valleytronics research. Their low energy spectrum can be described by Dirac cones on the corners of Brillouin zone, but the physical properties are richer than those of graphene since the spin degeneracy is lifted and the optical selection rules are valley dependent. This has been exploited for the optical injection of spin and valley polarized currents by the application of static electric fields. In this paper we consider an all-optical method for the injection of charge, spin and valley polarized currents. The presence of both a fundamental optical field and its second harmonic can lead to the injection of currents due to a nonlinear effect involving the quantum interference between one- and two-photon absorption processes. We analyze how the injected quantities can be controlled through the parameters of the incident light fields, allowing capabilities of control beyond those achieved with static fields, and discuss the conditions for experimental verification of our results.