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O: Fachverband Oberflächenphysik

O 95: 2D Materials: Stacking and heterostructures (joint session O/HL/TT)

O 95.2: Vortrag

Freitag, 13. März 2026, 09:45–10:00, HSZ/0401

Anisotropic Strain Observation in Naturally Occurring Buckling on Twisted Bilayer Graphene: A Nano-Raman Study — •Gustavo Soares¹, Rafael R. Barreto¹, Rafael Nadas¹, Kenji Watanabe², Takashi Taniguchi², Leonardo C. Campos¹, Luiz G. Cancado¹, and Angelo Malachias¹ — ¹Physics Department, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, 31270-901, Brazil — ²National Institute for Materials Science, Tsukuba, Ibaraki, 3050047, Japan

This work investigates naturally occurring buckling and its relation with anisotropic strain relaxation in twisted bilayer graphene (tBG). In the tBG system a twist angle is imposed to influence graphene structural and electronic properties. Such condition directly implies in the occurrence of biaxial in-plane strain, with usual observation of buckled/wrinkled localized regions where the tBG morphology is no longer planar. Using tip-enhanced Raman spectroscopy, we conducted high-resolution mapping to analyze variations in Raman bands associated with twist angle variation and strain effects. Our findings reveal that localized strain gradients, modulated by twist angle variations, induce deterministic buckling in graphene layers, evidencing distinct uniaxial and biaxial strain regions. Finite element modeling further supports these observations, showing that buckling can store elastic energy sufficient to overcome usual tBG-substrate adhesion forces.

Keywords: Twisted bilayer graphene; tip-enhanced Raman spectroscopy; twist angle distribution; strain profile