Field-tunable spin-valley transport in monolayer MoS$_2$

TL;DR

This paper demonstrates how off-resonant elliptically polarized light can dynamically control spin-valley transport in monolayer MoS$_2$, enabling optically reconfigurable valleytronic and spintronic devices.

Contribution

It introduces a theoretical framework for manipulating spin-valley transport in MoS$_2$ using laser-driven Floquet engineering, with exact analytic transmission solutions.

Findings

Laser tuning modifies spin-valley propagation thresholds.

Controllable pass/stop bands via laser intensity and polarization.

Valley contrast persists in Landauer conductance.

Abstract

We study field-controlled spin-valley transport in monolayer MoS$_2$ through a single electrostatic barrier and a uniform off-resonant elliptically polarized irradiation. Starting from the massive Dirac Hamiltonian with intrinsic spin-orbit coupling, we use a high-frequency Floquet expansion to obtain an effective static model with a laser-renormalized mass (gap) term. We solve the scattering problem by spinor matching and derive the exact analytic expression for the transmission. The numerical results show that the drive tunes both the spin-valley-dependent propagation threshold inside the barrier and the Fabry-P\'erot phase, creating controllable pass/stop bands. By varying both the laser intensity (amplitude) and the polarization shape, we show that the same junction can be switched between broadband valley filtering and resonance-selective operation, and the valley contrast remains visible in the Landauer conductance. Our findings establish an efficient route for realizing optically reconfigurable valleytronic and spintronic functionalities in MoS$_2$.