Disorder Dependent Valley Properties in Monolayer WSe2

TL;DR

This study explores how disorder affects valley polarization and coherence in monolayer WSe2, revealing that disorder significantly impacts valley coherence but not polarization, with implications for valleytronic applications.

Contribution

It provides the first detailed analysis of disorder's differential impact on valley coherence and polarization in monolayer WSe2 using photoluminescence polarization measurements.

Findings

Valley coherence decreases with increased disorder (Stokes Shift).

Valley polarization remains largely unaffected by disorder.

Valley coherence is more sensitive to disorder than valley polarization.

Abstract

We investigate the effect on disorder potential on exciton valley polarization and valley coherence in monolayer WSe2. By analyzing polarization properties of photoluminescence, the valley coherence (VC) and valley polarization (VP) is quantified across the inhomogeneously broadened exciton resonance. We find that disorder plays a critical role in the exciton VC, while minimally affecting VP. For different monolayer samples with disorder characterized by their Stokes Shift (SS), VC decreases in samples with higher SS while VP again remains unchanged. These two methods consistently demonstrate that VC as defined by the degree of linearly polarized photoluminescence is more sensitive to disorder potential, motivating further theoretical studies.