Hidden States and Dynamics of Fractional Fillings in tMoTe2 Moiré Superlattices

Abstract

The fractional quantum anomalous Hall (FQAH) effect was recently discovered in twisted MoTe2 bilayers (tMoTe2). Experiments to date have revealed Chern insulators from hole doping at v = -1, -2/3, -3/5, and -4/7 (per moiré unit cell). In parallel, theories predict that, between v = -1 and -3, there exist exotic quantum phases, such as the coveted fractional topological insulators (FTI), fractional quantum spin Hall (FQSH) states, and non-abelian fractional states. Here we employ transient optical spectroscopy on tMoTe2 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 pseudo gaps, leading to the disordering (melting) of correlated states. A probe pulse detects the subsequent melting and recovery dynamics via exciton and trion sensing. Besides the known states, we observe additional fractional fillings between v = 0 and -1 and a large number of states on the electron doping side (v > 0). Most importantly, we observe new states at fractional fillings of the Chern bands at v = -4/3, -3/2, -5/3, -7/3, -5/2, and -8/3. These states are potential candidates for the predicted exotic topological phases. Moreover, we show that melting of correlated states occurs on two distinct time scales, 2-4 ps and 180-270 ps, attributed to electronic and phonon mechanisms, respectively. We discuss the differing dynamics of the electron and hole doped states from the distinct moiré conduction and valence bands.

19 pages, 4 figures, 13 extended figures

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Cited by in corpus (10)

• Fractional Chern Insulator and Quantum Anomalous Hall Crystal in Twisted MoTe${}_2$
• Characterization of fractional Chern insulator quasiparticles in twisted homobilayer MoTe${}_2$
• Twistronics and moiré superlattice physics in 2D transition metal dichalcogenides
• Candidate for a Fractional Topological Insulator in Twisted MoTe2
• Kekulé order from diffuse nesting near higher-order Van Hove points
• Propagating Collective Spin-valley Modes in Twisted WSe2
• Dual-Polarization SHG Interferometry for Imaging Antiparallel Domains and Stacking Angles of 2D Heterocrystals
• Engineering topological exciton structures in two-dimensional semiconductors by a periodic electrostatic potential
• Intervalley Band Crossing and Transition of Fractional Chern Insulators in Floquet Twisted Bilayer MoTe${}_2$
• Topological Order Without Band Topology in Moiré Graphene