Sommaire:

Twisting two graphene monolayers creates a moiré superlattice that hosts diverse exotic phases [1]—such as superconductivity, correlated insulators, nematic order, Chern insulators, magnetic polarization, and strange-metal behavior. These arise from strong band reconstruction caused by interlayer tunneling and twist. At the “magic” angle (~1°), the moiré bands flatten, amplifying Coulomb interactions and enabling many interaction-driven quantum phases [2]. Moiré superlattices have also been realized in other 2D materials, including twisted MoTe₂, WSe₂, and multilayer graphene aligned with hexagonal boron nitride. Recent experiments have, for the first time, observed fractional Chern insulating phases in twisted MoTe₂ [3] and rhombohedral pentalayer graphene [4]. These remarkable states, theoretically predicted in the early 20LFs, represent fractional quantum Hall phases that emerge without an external magnetic field. In this talk, I will first give a broad introduction to moiré materials, then discuss two topics: the predicted Chern mosaic in trilayer graphene [5] and the physical origin of a fictitious magnetic field in moiré fractional Chern insulators [6]. [1] E. Y. Andrei, A. H. MacDonald, Nature Materials 19, 1265 (2020) [2] Cao et al., Nature 556, 80 (2018) [3] Kang, Shen, Qiu, Zeng, Xia, Watanabe, Taniguchi, Shan, and Mak. Nature 628, 522–526 (2024) [4] Lu, Han, Yao, Reddy, Yang, Seo, Watanabe, Taniguchi, Fu and Long, Nature (2023) [5] D. Guerci, Y. Mao, C. Mora, PRR 6, L022025 (2024) [6] K. Kolář, K. Yang, F. von Oppen, C. Mora, PRB 1LF, 115114 (2024)

Pour plus d'informations, merci de contacter Cassabois G.