Reversible engineering the spin-orbit coupling of monolayer MoS2 via laser irradiation under controlled gas atmospheres

TL;DR

This study demonstrates a reversible method to tune the spin-orbit coupling in monolayer MoS2 using laser irradiation in controlled atmospheres, enabling room-temperature control of electronic properties for spintronics applications.

Contribution

It introduces a novel, reversible laser-based technique to engineer spin-orbit coupling in monolayer MoS2 under ambient conditions, which was previously challenging.

Findings

Spin-orbit splitting can be tuned from 120 meV to 200 meV.

Photoluminescence intensity of B exciton can be inverted over 2 orders of magnitude.

The engineering mechanism involves band renormalization and increased absorption.

Abstract

Monolayer transition metal dichalcogenides (TMDs) with strong spin-orbit coupling combined with broken inversion symmetry, leading to a coupling of spin and valley degrees of freedom, make these materials highly interesting for potential spintronics and valleytronic applications. However, engineering the spin-orbit coupling (SOC) at room temperature as demand after device fabrication is still a great challenge for their practical applications. Here we reversibly engineer the spin-orbit coupling of monolayer MoS2 by laser irradiation under controlled gas environments, where the spin-orbit splitting has been effectively regulated within 120 meV to 200 meV. Furthermore, the photoluminescence (PL) intensity of B exciton can be invertible manipulation over 2 orders of magnitude. We attribute the engineering of spin-orbit splitting to the reduction of binding energy combined with band renormalization, originating from the enhanced absorption coefficient of monolayer MoS2 under inert gases and subsequent the significantly boosted carrier concentrations. Reflectance contrast spectra during the engineering stage provide unambiguous proof to support our interpretation. Our approach offers a new avenue to actively control the SOC strength in TMDs materials at room temperature and paves the way for designing innovative spintronics devices.