Deep Moiré Potentials in Twisted TMD heterobilayers

Twisted transition metal dichalcogenides (TMD) heterobilayers are a powerful platform to study interlayer excitonic states and charge confinement due to long wavelength periodic potentials produced by moiré patterns. Here we report the experimental observation of deep (>0.3 eV) moiré potentials in WSe₂/MoSe₂ heterobilayers using scanning tunneling microscopy (STM). We investigated the structural and electronic properties of nearly R-stacked (0 degree) and H-stacked (60 degrees) at small twist angles. Our spectroscopic measurements demonstrate a non-monotonic dependence of the moiré potential as a function of moiré wavelength in H-stacked heterobilayers. This non-monotonicity is directly linked to a drastic change in the structure of the moiré unit cell and the emergence of one-dimensional soliton domain walls at long moiré wavelength. We find that the magnitude of the moiré potential cannot be explained solely by interlayer hybridization, but is instead dominated by the three-dimensional structure and strain present within individual moiré unit cells.