  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.
