Transition metal dichalcogenides (TMDs) provide a powerful platform for exploring strongly correlated electronic phases in two dimensions, owing to reduced dielectric screening, large effective masses, and electrostatic tunability. In moiré heterostructures, a long-wavelength periodic potential enables carrier localization and stabilizes generalized Wigner crystal states at commensurate fractional fillings.

In this talk, I will present experimental evidence that Wigner crystallization in TMD moiré systems extends beyond simple commensurate ordering. We probe carrier correlations via an excitonic branch arising from Umklapp–Bragg scattering of repulsive exciton polarons, providing a direct spectroscopic fingerprint of the underlying electronic order. As the hole density is increased, the energy splitting between the repulsive polaron and the Umklapp-induced excitonic feature evolves step-wise, forming distinct plateaus centered at commensurate fractional fillings of the moiré lattice. These observations reveal a hierarchy of commensurate and incommensurate phases, consistent with a so-called Devil’s staircase of generalized Wigner crystal states.

I will conclude by discussing the implications of these results for understanding correlated phases in moiré materials and emergent electronic order.