| Brief Bio of the Speaker | Jie Wang, graduated as Bachelor from USTC in 2013, and as PhD from Princeton University in 2019. After three years as postdoc fellow at Flatiron Institute of the Simons Foundation, he is currently a postdoc fellow at Harvard University since 2022. He will join Temple University as assistant professor in 2024. His research interest includes topological quantum material and electron correlation. |
Abstract | “Moiré” materials produced by stacking monolayers with small relative twist angles are of intense current interest for the range of correlated electron phenomena they exhibit and for their high degree of experimental controllability. Controlling moiré to realize exotic quantum phase of matter is important for both fundamental science research and future application to quantum information sciences. This talk focus on the fractional Chern insulator phase (FCI), the analogy of fractional quantum Hall effect in the absence of external magnetic fields. Concretely, this talk presents a new exact geometric criterion for the stability of FCI and discuss its implication to moiré TMD material (MoTe2). The common wisdom is to engineer material to approach “Landau level limit” to stabilize FCI. This talk will disprove such common lore by showing a new theory (ideal flatband theory) which emphasizes the fundamental importance of “quantum geometries of wavefunctions” [1-3]. The new theory points to a large family of flatband systems that stabilize FCIs exactly beyond the conventional Landau level limit. It has a wide range of application to 2D material design, including twisted bilayer graphene, moiré TMD material, vortex lattice systems [4] and others. It has direct implication for the recently experimental observed FCI in twisted MoTe2 material [5-6].
References： [1] J. Wang et al., Exact Landau level description of geometry and interaction in a flatband, PRL 127, 246403 (2021). [2] J. Wang et al., Hierarchy of ideal flatbands in chiral twisted multilayer graphene models, PRL 128, 176403 (2022). [3] J. Wang et al., Origin of model fractional Chern insulators in all topological ideal flatbands PRR 5, 023167 (2023). [4] Dong, J. Wang, Liang Fu, Dirac electron under periodic magnetic field, arXiv 2208.10516 (2022). [5] Dong, J. Wang, Ledwith, Vishwanath, Parker, Composite Fermi liquid at zero magnetic field in twisted MoTe2, arXiv: 2306.01719 (2023). [6] J. Wang et al., Lattice Monte Carlo for quantum Hall effect on torus, PRB 99,125123 (2019). |
