Strain and twist angle driven electronic structure evolution in twisted bilayer graphene

作者：Jiawei Yu, Guihao Jia, S. X. Li, Zhen Zhan, Yuyang Wang, Kebin Xiao, Yongkang Ju, Hongyun Zhang, Zhiqiang Hu, Yu Guo, Biao Lian, Peizhe Tang, Pierre Anthony Pantaleón, Shuyun Zhou, F. Guinea, Qi-Kun Xue, Wei Li · 发表于：Reports on Progress in Physics · 年份：2026 · DOI：10.1088/1361-6633/ae544f · 被引用次数：3 · 研究领域：Graphene research and applications、2D Materials and Applications、Topological Materials and Phenomena

In twisted bilayer graphene (TBG) devices, local strain frequently coexists with the twist-angle-dependent moiré superlattice and strongly influences the electronic properties, yet their combined effects remain incompletely understood. Here, using low-temperature scanning tunneling microscopy, we study a TBG device exhibiting both a continuous twist-angle gradient from 0.35° to 1.30° and spatially varying strain fields, spanning the first (1.1°), second (0.5°), and third (0.3°) magic angles. We directly visualize the evolution of flat and remote bands in both energy and real space with atomic resolution. By comparing regions dominated by shear, uniaxial, and mixed strain, we find that shear strain plays a decisive role in controlling flat-band separation, linewidth, and spectral-weight redistribution. Near the first magic angle, this manifests as an anomalous transfer of spectral weight between the two flat-band peaks, accompanied by an unusual spatial dispersion of flat-band states within a moiré unit cell. In contrast, the energy of the remote bands provides a robust, strain-insensitive indicator of the local twist angle. Structural analysis reveals that shear strain dominates over large regions of the sample, consistent with its lower elastic energy cost. All observations are quantitatively reproduced by a continuum model incorporating heterostrain and electron-electron interactions, establishing shear strain as a central ingredient in shaping the low-energy electronic lan...