Photo-modulation of the spin Hall conductivity of mono-layer transition metal dichalcogenides

TL;DR

This paper explores how off-resonant light can optically tune the spin Hall conductivity in mono-layer transition metal dichalcogenides by rearranging their band structures, with implications for spintronic applications.

Contribution

It introduces a method to optically modulate spin Hall conductivity in 2D materials using Floquet theory, providing quantitative analysis and comparison between different materials.

Findings

Spin Hall conductivity decreases at higher frequencies and lower light intensities.

WSe₂ exhibits larger spin Hall conductivity than MoS₂ under similar conditions.

Off-resonant light does not excite electrons but alters band structure, affecting spin transport.

Abstract

We report on a possible optical tuning of the spin Hall conductivity in mono-layer transition metal dichalcogenides. Light beams of frequencies much higher than the energy scale of the system (the \textit{off-resonant} condition) does not excite electrons but rearranges the band structure. The rearrangement is quantitatively established using the Floquet formalism. For such a system of mono-layer transition metal dichalcogenides, the spin Hall conductivity (calculated with the Kubo expression in presence of disorder) exhibits a drop at higher frequencies and lower intensities. Finally, we compare the spin Hall conductivity of the higher spin-orbit coupled WSe$_{2} $ to MoS$_{2} $; the spin Hall conductivity of WSe$_{2}$ was found to be larger.