Abstract
The long-wavelength moiré superlattices in twisted 2D structures have emerged as a highly tunable platform for strongly correlated electron physics. We study the moiré bands in twisted transition metal dichalcogenide homobilayers, focusing on WSe2, at small twist angles using a combination of first principles density functional theory, continuum modeling, and Hartree-Fock approximation. We reveal the rich physics at small twist angles θ < 4∘, and identify a particular magic angle at which the top valence moiré band achieves almost perfect flatness. In the vicinity of this magic angle, we predict the realization of a generalized Kane-Mele model with a topological flat band, interaction-driven Haldane insulator, and Mott insulators at the filling of one hole per moiré unit cell. The combination of flat dispersion and uniformity of Berry curvature near the magic angle holds promise for realizing fractional quantum anomalous Hall effect at fractional filling. We also identify twist angles favorable for quantum spin Hall insulators and interaction-induced quantum anomalous Hall insulators at other integer fillings.
| Original language | English |
|---|---|
| Article number | 6730 |
| Journal | Nature Communications |
| Volume | 12 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 2021 |
Funding
We thank Kin Fai Mak, Jie Shan, Tingxin Li, and Shengwei Jiang for ongoing collaborations on MoTe2/WSe2, Bi Zhen and Constantin Schrade for previous collaborations on related topics. We thank Pablo Jarillo-Herrero, Kenji Yasuda, Cory Dean, Abhay Pasupathy, Qianhui Shi, Augusto Ghiotto, and En-Min Shih for helpful discussions. This work is primarily supported by the DOE Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-SC0020149 (band structure calculation), DE-SC0018945 (theoretical modeling), and Simons Investigator award from the Simons Foundation (numerical analysis). L.F. is partly supported by the David and Lucile Packard Foundation.