Moire physics in transition metal dichalcogenides

I will survey recent advances in van der Waals heterostructures formed by stacking two layers of transition metal dichalcogenides (TMD). When the two layers have a small lattice mismatch or rotational misalignment, a long-wavelength moire structure emerges and produces narrow minibands in the electron energy spectrum. Strong electron interaction effects in these minibands give rise to a remarkable variety of quantum states, including Mott/charge transfer insulators, generalized Wigner crystals, and the quantum anomalous Hall state. I will introduce a theoretical description based on generalized Hubbard model to explain these diverse phenomena in a unified way. In particular, the newly discovered quantum anomalous Hall state in MoTe2/WSe2 arises from inverted charge transfer gap in a Mott insulator [1]. Doping charge transfer insulators in TMD moire materials may give rise to pair density wave and unconventional superconducting states [2,3].

[1] T. Devakul and L. Fu, arXiv:2109.13909 (to appear in PRX)   

[2] K. Slagle and L. Fu, Phys. Rev. B 102, 235423 (2020)

[3] V. Crépel and L. Fu, Science Advances 7, eabh2233 (2021)