Description
Emergent strongly correlated electronic phenomena in atomically thin transition-metal dichalcogenides represent an exciting frontier in condensed matter physics, with examples ranging from bilayer superconductivity and electronic Wigner crystals to the ongoing search for exciton condensation.
Here, we report experimental signatures of unconventional coupling of interlayer excitons consistent with coherence between electrons in different layers of a naturally grown MoS₂ homobilayer. When the bilayer is electron-doped under conditions where tunnelling between layers is negligible, we observe that two interlayer excitons – which normally should not interact – hybridize in a way distinct from both conventional level crossing and anti-crossing. We show that these observations can be explained by quasi-static random coupling between the excitons, which increases with electron density and decreases with temperature. We argue that this phenomenon is indicative of a spatially fluctuating order parameter in the form of interlayer electron coherence – a theoretically predicted many-body state that has yet to be unambiguously established experimentally outside the quantum Hall regime.
