Fractional Chern Insulator in Twisted Bilayer MoTe2

A recent experiment has reported the first observation of a zero -field fractional Chern insulator (FCI) phase in twisted bilayer MoTe2 moire superlattices [J. Cai et al., Signatures of fractional quantum anomalous Hall states in twisted MoTe2, Nature (London) 622, 63 (2023).]. The experimental observation is at an unexpected large twist angle 3.7 degrees and calls for a better understanding of the FCI in real materials. In this Letter, we perform large-scale density functional theory calculation for the twisted bilayer MoTe2 and find that lattice reconstruction is crucial for the appearance of an isolated flat Chern band. The existence of the FCI state at li = -2/3 is confirmed by exact diagonalization. We establish phase diagrams with respect to the twist angle and electron interaction, which reveal an optimal twist angle of 3.5 degrees for the observation of FCI. We further demonstrate that an external electric field can destroy the FCI state by changing band geometry and show evidence of the li = -3/5 FCI state in this system. Our research highlights the importance of accurate single -particle band structure in the quest for strong correlated electronic states and provides insights into engineering fractional Chern insulator in moire superlattices.