Two-Dimensional Moir\'e Polaronic Electron Crystals

TL;DR

This paper investigates the stability and melting dynamics of Mott states in WSe2/WS2 moiré superlattices, revealing significant electron-phonon coupling and polaron formation that influence correlated electron phases.

Contribution

It provides new insights into the interplay of electron-electron and electron-phonon interactions in stabilizing polaronic Mott insulators in 2D moiré materials.

Findings

Ultrafast excitation melts Mott states on longer timescales than predicted.

Melting rates are thermally activated with specific activation energies.

DFT confirms polaron formation with a binding energy of 16 meV.

Abstract

Two-dimensional moir\'e materials have emerged as the most versatile platforms for realizing quantum phases of electrons. Here, we explore the stability origins of correlated states in WSe2/WS2 moir\'e superlattices. We find that ultrafast electronic excitation leads to melting of the Mott states on time scales five times longer than predictions from the charge hopping integrals and the melting rates are thermally activated, with activation energies of 18 and 13 meV for the one- and two-hole Mott states, respectively, suggesting significant electron-phonon coupling. DFT calculation of the one-hole Mott state confirms polaron formation and yields a hole-polaron binding energy of 16 meV. These findings reveal a close interplay of electron-electron and electron-phonon interactions in stabilizing the polaronic Mott insulators at transition metal dichalcogenide moir\'e interfaces.