Confined Trions and Mott-Wigner States in a Purely Electrostatic Moiré Potential

Moir´e heterostructures consisting of transition metal dichalcogenide (TMD) heterobilayers and homobilayers have emerged as a promising material platform to study correlated electronic states. Optical signatures of strong correlations in the form of Mott-Wigner states and fractional Chern insulators have already been observed in TMD monolayers and their twisted bilayers. In this work, we use a moir´e substrate containing a twisted hexagonal boron nitride (h-BN) interface to externally generate a superlattice potential for the TMD layer: The periodic structure of ferroelectric domains in h-BN creates a purely electrostatic potential for charge carriers. We find direct evidence for the induced moir´e potential in the emergence of new excitonic resonances at integer fillings and our observation of an enhancement of the trion binding energy by ≃3 meV. A theoretical model for exciton-electron interactions allows us to directly determine the moir´e potential modulation of 30 5 meV from the measured trion binding energy shift. We obtain direct evidence for charge order linked to electronic Mott-Wigner states at filling factors ν ¼ 1=3 and ν ¼ 2=3 through the associated exciton umklapp resonances.