Twisted WSe₂ as a Candidate Chern Insulator

TMD twisted homobilayers have been proposed to be an ideal platform for studying strong correlation phenomena, as exemplified by the recent discovery of fractional quantum anomalous Hall effect (FQAHE) in twisted MoTe₂^{1, 2}. The K valley position, which needs to be at the valence band maximum, and the layer pseudospin configuration, which needs to include opposite layer polarizations at different points within the moiré unit cell, are the key ingredients needed to support FQAHE states. The layer pseudospin texture of K valley carriers underlies the moiré pseudomagnetic field (real-space Berry curvature) for realizing the Kane-Mele/Haldane model³.



Here we report on experimental evidence that twisted WSe₂ bilayers might be another good candidate. Our constant height scanning tunneling spectroscopies (CHSTS) reveal the moiré potential modulation for G-valley. Using constant current STS, we map out the electronic state of the K-valley within the moiré superlattice revealing that the K-valley states are at the VBM. In addition, K-valley STS mapping reveals opposite polarizations of the wavefunction between the MX and XM sites, establishing the theoretically predicted pseudospin texture.

[1] Park, H.et al., Nature 622, 74–79 (2023).

[2] Nicolás Morales-Durán et al. arXiv:2308.03143

[3] Yu et. al., National Science Review 7, 1, 12–20 (2020)