Valley spin-acoustic resonance in MoS${\bf _2}$ monolayers

TL;DR

This paper investigates how surface acoustic waves induce spin-flip transitions in monolayer MoS₂, leading to a spin-acoustic resonance that is tunable by magnetic fields, revealing new spin-mechanical coupling phenomena.

Contribution

It introduces the concept of valley spin-acoustic resonance in MoS₂ monolayers and demonstrates how magnetic fields can control this resonance through valley splitting.

Findings

Surface acoustic waves induce spin-flip transitions in MoS₂.

Magnetic fields cause valley-selective splitting of the resonance.

Resonance affects surface acoustic wave absorption and acoustoelectric current.

Abstract

The band structure of a monolayer MoS$_2$ comprises of spin-split subbands, owing to the mutual presence of broken inversion symmetry and strong spin-orbit coupling. In the conduction band, spin-valley coupled subbands cross each other at finite momenta, and they are valley-degenerate. When exposed to surface acoustic waves, the emerging strain-induced effective magnetic field can give rise to spin-flip transitions between the spin-split subbands in the vicinity of subbands crossing point, resulting in the emergence of a spin-acoustic resonance and the acoustoelectric current. An external magnetic field breaks the valley degeneracy resulting in the valley-selective splitting of spin-acoustic resonances both in surface acoustic wave absorption and acoustoelectric current.