Real-space observation of a time-reversal invariant topological state in twisted bilayer InSe

作者：Dacheng Tian, Shengdan Tao, Yu Wang, Peng Cheng, Yi‐Qi Zhang, Kehui Wu, Zeying Zhang, Shengyuan A. Yang, Baojie Feng, Yunhao Lu, Lan Chen · 发表于：Nature Communications · 年份：2025 · DOI：10.1038/s41467-025-64535-3 · 被引用次数：1 · 研究领域：Topological Materials and Phenomena、Advanced Semiconductor Detectors and Materials、Phase-change materials and chalcogenides

The moiré superlattice formed by van der Waals (vdW) stacking of two-dimensional (2D) monolayers with a twist angle can give rise to a variety of novel correlated physical phenomena. In this study, we propose that a 2D semiconductor composed of vdW layers with band edge states extended into the interlayer region can host time-reversal-invariant topological states, as demonstrated by density functional theory and tight-binding calculations. This emergent physics in moiré superlattices is experimentally verified in a twisted bilayer InSe with a twisting angle of θ = 7.34°. Using scanning tunneling microscopy/spectroscopy (STM/STS), we observed topological edge modes associated with the Z2 topological metal state at the moiré domain boundary, while these states are absent in the bilayer without twisting. Our theoretical predictions and experimental discoveries advance the field of moiré physics and twistronics, offering a promising strategy for the creation of moiré topological devices. Time-reversal invariant topological states in twisted 2D semiconductors have been previously reported, but their direct visualization in real space has remained elusive. Here, the authors report scanning tunnelling microscopy/spectroscopy measurements of twisted bilayer InSe, showing the formation of magnetic-field sensitive topological edge modes at the moiré domain boundary.