Van der Waals bilayers with a small difference in the lattice constant and/or orientation have long-period moiré patterns, which provide vast new opportunities to control material properties. In this talk, I will present our work on moiré pattern physics that arise from an interplay of symmetry, topology and many-body interactions. First, I will describe our theoretical proposal of using twisted bilayer transition metal dichalcogenides as quantum simulators of Hubbard model [1, 2], and discuss recent experimental realizations. Then I will focus on twisted bilayer graphene (TBG) and show how the interplay between many-body interactions and Bloch band symmetry of TBG can lead to unconventional superconductivity [3, 4]. Finally, I will discuss quantum anomalous Hall insulators in TBG and demonstrate their stability against spin/valley magnon excitations [5]. I will describe the effects of quantum geometry on spin stiffness and show that Berry curvature of moiré bands helps to stiffen spin magnons.

References

1. F. Wu, T. Lovorn, E. Tutuc, A. H. MacDonald, Phys. Rev. Lett. 121, 026402 (2018).

2. F. Wu, T. Lovorn, E. Tutuc, I. Martin, A. H. MacDonald, Phys. Rev. Lett. 122, 086402 (2019).

3. F. Wu, A. H. MacDonald, and I. Martin, Phys. Rev. Lett. 121, 257001 (2018).

4. F. Wu, E. Hwang, and S. Das Sarma, Phys. Rev. B 99, 165112 (2019).

5. F. Wu, S. Das Sarma, arXiv:1908.05417 (2019).