Imaging topological flat bands of twisted bilayer MoTe₂

Two-dimensional (2D) moiré materials have emerged as a highly tunable platform for investigating novel quantum states of matter arising from strong electronic correlations and nontrivial band topology. Recently, topological flat bands formed in 2D semiconducting moiré superlattices have attracted great interests. In particular, a series of topological quantum phases, including the long-sought fractional quantum anomalous Hall (FQAH) effect, have recently been experimentally observed in twisted bilayer MoTe₂ (tMoTe₂). However, the microscopic information of tMoTe₂ moiré superlattice and its electronic structure is still lacking. Here, we present scanning tunneling microscopy and spectroscopy (STM/STS) studies of the tMoTe₂ moiré superlattice. STM imaging reveals a pronounced in-plane lattice reconstruction with periodic strain redistribution in the tMoTe₂, which serves as gauge fields for generating topological moiré bands. Importantly, the electronic states of the low-energy moiré flat bands primarily concentrate at the XM and MX regions as revealed by STS imaging. Such spatial distributions are nicely reproduced by our first principal calculations with a large-scale basis, suggesting the low-energy moiré flat bands are formed through the hybridization of K valley bands of the top layer and K’ valley bands of the bottom layer. Overall, our findings provide compelling real-space evidence of topological flat bands of tMoTe₂, paving the way for further STM/STS investigations of correlated topological states within the topological flat band in gate-tunable tMoTe₂ devices.