Spin-valley relaxation dynamics of Landau-quantized electrons in MoSe$_2$ monolayer

TL;DR

This study explores how Landau-quantized electrons in a MoSe2 monolayer relax their spin-valley polarization after optical excitation, revealing dependence on quantum Hall states and potential for probing disorder and interactions.

Contribution

It demonstrates the dependence of spin-valley relaxation rates on Landau level filling factors in a MoSe2 monolayer under strong magnetic fields, highlighting new insights into relaxation dynamics.

Findings

Relaxation rate varies with Landau level filling factor.

Faster relaxation at integer quantum Hall states.

Slower relaxation at non-integer fillings.

Abstract

Non-equilibrium dynamics of strongly correlated systems constitutes a fascinating problem of condensed matter physics with many open questions. Here we investigate the relaxation dynamics of Landau-quantized electron system into spin-valley polarized ground state in a gate-tunable MoSe$_2$ monolayer subjected to a strong magnetic field. The system is driven out of equilibrium with optically injected excitons that depolarize the electron spins and the subsequent electron spin-valley relaxation is probed in time-resolved experiments. We demonstrate that the relaxation rate at millikelvin temperatures sensitively depends on the Landau level filling factor: it becomes faster whenever the electrons form an integer quantum Hall liquid and slows down appreciably at non-integer fillings. Our findings evidence that valley relaxation dynamics may be used as a tool to investigate the interplay between the effects of disorder and strong interactions in the electronic ground state.