Heonjoon Park1,Jiaqi Cai1,Eric Anderson1,Yinong Zhang1,Jiayi Zhu1,Xiaoyu Liu1,Chong Wang1,William Holtzmann1,Chaowei Hu1,Zhaoyu Liu1,Takashi Taniguchi2,Kenji Watanabe2,Jiun-Haw Chu1,Ting Cao1,Liang Fu3,Wang Yao4,Cui-Zu Chang5,David Cobden1,Di Xiao1,Xiaodong Xu1
University of Washington1,National Institute for Materials Science2,Massachusetts Institute of Technology3,The University of Hong Kong4,The Pennsylvania State University5
Heonjoon Park1,Jiaqi Cai1,Eric Anderson1,Yinong Zhang1,Jiayi Zhu1,Xiaoyu Liu1,Chong Wang1,William Holtzmann1,Chaowei Hu1,Zhaoyu Liu1,Takashi Taniguchi2,Kenji Watanabe2,Jiun-Haw Chu1,Ting Cao1,Liang Fu3,Wang Yao4,Cui-Zu Chang5,David Cobden1,Di Xiao1,Xiaodong Xu1
University of Washington1,National Institute for Materials Science2,Massachusetts Institute of Technology3,The University of Hong Kong4,The Pennsylvania State University5
The interplay of topology, magnetism, and strong correlation leads to intriguing quantum states of matter. A prominent example is the quantum anomalous Hall effect (QAHE), which displays integer quantum Hall effect at zero magnetic field due to topologically nontrivial bands and intrinsic magnetism. Realizing a similar analogue of the fractional quantum Hall effect at zero field, known as the fractional quantum anomalous Hall effect (FQAHE), has long posed a challenge due to stringent constraints in electron-electron interaction and quantum geometry. Here, we present the experimental observation of FQAHE and electrically tunable topological phase transition in twisted MoTe2 bilayer using electrical transport measurements. In addition, an anomalous Hall state emerges near the filling factor -1/2. Its behavior mirrors that of the composite Fermi liquid in the half-filled lowest Landau level of a two-dimensional electron gas under high magnetic fields. The direct observation of the FQAH and associated effects opens the door to exploring charge fractionalization and anyonic statistics at zero magnetic field.