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

TY - JOUR

T1 - Strain and twist angle driven electronic structure evolution in twisted bilayer graphene

AU - Yu, Jiawei

AU - Jia, Guihao

AU - Li, Qian

AU - Zhan, Zhen

AU - Wang, Yuyang

AU - Xiao, Kebin

AU - Ju, Yongkang

AU - Zhang, Hongyun

AU - Hu, Zhiqiang

AU - Guo, Yunkai

AU - Lian, Biao

AU - Tang, Peizhe

AU - Pantaleón, Pierre A.

AU - Zhou, Shuyun

AU - Guinea, Francisco

AU - Xue, Qi Kun

AU - Li, Wei

N1 - Publisher Copyright: © 2026 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.

PY - 2026/4/1

Y1 - 2026/4/1

N2 - 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 landscape of TBG.

AB - 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 landscape of TBG.

KW - 2D materials

KW - scanning tunneling microscopy and spectroscopy

KW - strain engineering

KW - twisted bilayer graphene

KW - twistronics

UR - https://www.scopus.com/pages/publications/105034947907

UR - https://www.scopus.com/pages/publications/105034947907#tab=citedBy

U2 - 10.1088/1361-6633/ae544f

DO - 10.1088/1361-6633/ae544f

M3 - Article

C2 - 41849817

SN - 0034-4885

VL - 89

JO - Reports on Progress in Physics

JF - Reports on Progress in Physics

IS - 4

M1 - 048001

ER -