Extended Data Fig. 3: Mott insulator state revealed by the interlayer exciton photoluminescence.
From: Correlated interlayer exciton insulator in heterostructures of monolayer WSe2 and moiré WS2/WSe2
a, The two-dimensional color plot of derivative reflection contrast spectra of 2s exciton at E = 80 mV nm−1. Well-defined and red-shifted monolayer WSe2 2s exciton resonances at p/p0 = 1 and 2 correspond to the Mott insulator and the full filling of the moiré band (that is, two holes per moiré superlattice). b, The two-dimensional color plot of interlayer exciton PL spectra of the WS2/WSe2 moiré bilayer at E = 80 mV nm−1. The PL resonance energy blueshifts suddenly, and the PL intensity exhibits a sudden increase at p/p0 = 1 and 2, which is consistent with the correlated states probed by the 2s exciton spectra. Therefore, this abrupt increase of interlayer exciton PL intensity provides a reliable signature of the Mott insulating state with one hole at each moiré superlattice (pmoiré /p0 = 1 or 2).
