Electrons surf phason waves in moiré bilayers

We investigate the effect of thermal fluctuations on the atomic and electronic structure of a twisted MoSe${}_2$/WSe${}_2$ heterobilayer using a combination of classical molecular dynamics and $\mathit{\text{ab-initio}}$ density functional theory calculations. Our calculations reveal that thermally excited phason modes give rise to an almost rigid motion of the moiré lattice. Electrons and holes in low-energy states are localized in specific stacking regions of the moiré unit cell and follow the thermal motion of these regions. In other words, charge carriers surf phason waves that are excited at finite temperatures. Small displacements at the atomic scale are amplified at the moiré scale, which gives rise to significant surfing speeds. We also show that such surfing survives in the presence of a substrate and disorder. This effect has potential implications for the design of charge and exciton transport devices based on moiré materials.