Electrons surf phason waves in moir\'e bilayers

TL;DR

This paper demonstrates that in twisted MoSe2/WSe2 heterobilayers, thermally excited phason modes cause charge carriers to surf on moiré lattice waves, influencing transport properties.

Contribution

It reveals how thermal fluctuations induce phason waves that enable charge carriers to surf in moiré bilayers, a phenomenon not previously characterized.

Findings

Charge carriers follow phason wave motion at finite temperatures.

Moiré lattice motion is almost rigid due to thermal excitations.

Surfing persists despite substrate and disorder effects.

Abstract

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 \textit{ab-initio} density functional theory calculations. Our calculations reveal that thermally excited phason modes give rise to an almost rigid motion of the moir\'e lattice. Electrons and holes in low-energy states are localized in specific stacking regions of the moir\'e 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 moir\'e 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 moir\'e materials.