Optical Control of Slow Topological Electrons in Moir\'e Systems

TL;DR

This paper demonstrates how optical driving in moiré systems like twisted bilayer graphene can induce and control topological electronic states with slow dynamics, enabling tunable anomalous Hall effects.

Contribution

It introduces a method to optically control topological states in Floquet moiré materials, overcoming heating effects and decoupling from phonons to manipulate electronic properties.

Findings

High-Berry-curvature states can be driven into a slow regime.

Drive amplitude controls decoupling from phonons and Hall response.

Steady states are sensitive to drive parameters and measurable experimentally.

Abstract

Floquet moir\'e materials possess optically-induced flat-electron bands with steady-states sensitive to drive parameters. Within this regime, we show that strong interaction screening and phonon bath coupling can overcome enhanced drive-induced heating. In twisted bilayer graphene (TBG) irradiated by a terahertz-frequency continuous circularly polarized laser, the extremely slow electronic states enable the drive to control the steady state occupation of high-Berry curvature electronic states. In particular, above a critical field amplitude, high-Berry-curvature states exhibit a slow regime where they decouple from acoustic phonons, allowing the drive to control the anomalous Hall response. Our work shows that the laser-induced control of topological and transport physics in Floquet TBG are measurable using experimentally available probes.