Hidden states and dynamics of fractional fillings in twisted MoTe2 bilayers

• 成果类型: Article
• 署名作者: Wang, Yiping; Choe, Jeongheon; Anderson, Eric; Li, Weijie; Ingham, Julian; Arsenault, Eric A.; Li, Yiliu; Hu, Xiaodong; Taniguchi, Takashi; Watanabe, Kenji; Roy, Xavier; Basov, Dmitri; Xiao, Di; Queiroz, Raquel; Hone, James C.; Xu, Xiaodong; Zhu, X. -Y.
• 署名单位: Columbia University; Columbia University; University of Washington; University of Washington Seattle; Columbia University; University of Washington; University of Washington Seattle; National Institute for Materials Science; National Institute for Materials Science
• 刊物名称: Nature
• ISSN/ISSBN: 0028-3212
• DOI: 10.1038/s41586-025-08954-8
• 发表日期: 2025-05-29
• 关键词: moire; valley

摘要

The fractional quantum anomalous Hall (FQAH) effect was recently discovered in twisted MoTe2 (tMoTe(2)) bilayers(1, 2, 3-4). Experiments so far have revealed Chern insulators from hole doping at nu = -1, -2/3, -3/5 and -4/7 (per moir & eacute; unit cell)(1, 2, 3, 4, 5-6). In parallel, theories predict that, between v = -1 and -3, there exist exotic quantum phases(7, 8, 9, 10, 11, 12, 13, 14-15), such as the coveted fractional topological insulators, fractional quantum spin Hall (FQSH) states and non-Abelian fractional states. Here we use transient optical spectroscopy(16,17) on tMoTe(2) to reveal nearly 20 hidden states at fractional fillings that are absent in static optical sensing or transport measurements. A pump pulse selectively excites charge across the correlated or pseudogaps, leading to the disordering (melting) of correlated states(18). A probe pulse detects the subsequent melting and recovery dynamics by means of exciton and trion sensing(1,3,19, 20-21). Besides the known states, we observe further fractional fillings between nu = 0 and -1 and a large number of states on the electron doping side (nu > 0). Most importantly, we observe new states at fractional fillings of the Chern bands at nu = -4/3, -3/2, -5/3, -7/3, -5/2 and -8/3. These states are potential candidates for the predicted exotic topological phases(7, 8, 9, 10, 11, 12, 13, 14-15). Moreover, we show that melting of correlated states occurs on two distinct timescales, 2-4 ps and 180-270 ps, attributed to electronic and phonon mechanisms, respectively. We discuss the differing dynamics of the electron-doped and hole-doped states from the distinct moir & eacute; conduction and valence bands.