Twist-angle transferable continuum model and second flat Chern band in twisted MoTe2 and WSe2

TL;DR

This paper introduces a transferable continuum model for twisted TMD bilayers that accurately predicts electronic properties across various twist angles and reveals a second flat Chern band near 2 degrees, aiding the design of novel electronic phases.

Contribution

The authors develop a twist-angle transferable continuum model for tTMD homobilayers, incorporating DFT data and machine learning, enabling efficient exploration of electronic phases without extensive calculations.

Findings

Model accurately reproduces DFT band structures across twist angles.

A second flat Chern band appears near 2 degrees.

Model facilitates engineering of electronic phases in moiré TMDs.

Abstract

We develop a twist-angle transferable continuum model for twisted transition metal dichalcogenide (tTMD) homobilayers, using tMoTe2 and tWSe2 as examples. All model parameters are extracted from density functional theory (DFT) calculations at a single twist angle (3.89{\deg}) and monolayer data. Our model captures both lattice relaxation effects and the long-range behavior of piezoelectric and ferroelectric potentials. Leveraging lattice relaxations obtained via machine learning force fields (MLFFs), the model can be efficiently transferred to other twist angles without requiring additional DFT calculations. It accurately reproduces the DFT band dispersions and quantum geometries across a wide range of twist angles. Furthermore, our model reveals that a second flat Chern band arises near 2{\deg} when the interlayer potential difference becomes comparable to the interlayer tunneling. This continuum model provides a clear understanding and starting point for engineering novel electronic phases in moir\'e TMDs through twist angles and lattice relaxations.