Disorder induced 2D metal-insulator transition in moir\'e transition metal dichalcogenide multilayers

TL;DR

This paper presents a minimal theoretical model explaining the metal-insulator transition in 2D moiré transition metal dichalcogenides, attributing it to Coulomb disorder and impurity scattering, aligning with experimental observations.

Contribution

It introduces a simple Coulomb disorder-based theory for the 2D MIT in moiré TMDs, quantitatively matching experimental impurity levels.

Findings

Disorder of 5-10×10^10 cm^-2 explains most MIT phenomenology.

Carrier scattering by charged impurities induces the MIT.

The theory aligns qualitatively with experimental data.

Abstract

We develop a minimal theory for the recently observed metal-insulator transition (MIT) in two-dimensional (2D) moir\'e multilayer transition metal dichalcogenides (mTMD) using Coulomb disorder in the environment as the underlying mechanism. In particular, carrier scattering by random charged impurities leads to an effective 2D MIT approximately controlled by the Ioffe-Regel criterion, which is qualitatively consistent with the experiments. We find the necessary disorder to be around $5$-$10\times10^{10}$cm$^{-2}$ random charged impurities in order to quantitatively explain much, but not all, of the observed MIT phenomenology as reported by two different experimental groups. Our estimate is consistent with the known disorder content in TMDs.