Transport Theory of Monolayer Transition-Metal Dichalcogenides through Symmetry

TL;DR

This paper develops a transport theory explaining momentum and spin relaxation in monolayer transition-metal dichalcogenides, highlighting the role of flexural phonons and symmetry, with implications for spin dynamics and mobility.

Contribution

It introduces a comprehensive theory linking symmetry and flexural phonons to spin and momentum relaxation in 2D materials, revealing universal behaviors.

Findings

Ultrafast spin relaxation for electrons in free-standing membranes.

Supported membranes exhibit mitigated spin relaxation.

Inverse relation between mobility and spin relaxation due to flexural phonons.

Abstract

We present a theory that elucidates the major momentum and spin relaxation processes for electrons, holes and hot excitons in monolayer transition-metal dichalcogenides. We expand on spin flips induced by flexural phonons and show that the spin relaxation is ultrafast for electrons in free-standing membranes while being mitigated in supported membranes. This behavior due to interaction with flexural phonons is universal in two-dimensional membranes that respect mirror symmetry and it leads to a counterintuitive inverse relation between mobility and spin relaxation.