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MON: Monday Contributed Sessions

MON 23: Poster Session: Fundamental Aspects and Model Systems

MON 23.62: Poster

Monday, September 8, 2025, 18:30–20:30, ZHG Foyer 1. OG

Vacancies and Stone-Wales Defects in Twisted Bilayer Graphene: A Comparative Theoretical Study — •Fabian Dietrich and Eduardo Cisternas — Departamento de Ciencias Físicas, Universidad de La Frontera, Temuco, Chile

Twisted bilayer graphene (TBG) has emerged as a cornerstone in the exploration of strongly correlated electronic systems, exhibiting tunable quantum phenomena such as superconductivity and Mott insulating states. In this study, we present a comparative theoretical investigation of two key classes of structural defects - monovacancies and Stone-Wales (SW) defects - introduced into a TBG system with different twist angles.

Using density functional theory (DFT), we analyze the energetic stability, local geometric reconstruction, and electronic structure of these defects. Our results show that both types of defects significantly alter the local density of states (LDOS), introducing mid-gap states and modifying the flat bands characteristic of TBG. Notably, the influence of the defect type is highly sensitive to its registry within the Moiré supercell, with SW defects inducing less mid-gap perturbation than vacancies but more extensive topological rearrangements.

Our findings offer new insights into defect engineering in twisted van der Waals systems and have implications for designing quantum devices based on TBG with tailored electronic properties.
[1] F. Dietrich, U. Guevara, A. Tiutiunnyk, D. Laroze, E. Cisternas, Flatchem. 41 (2023) 100541.

Keywords: Twisted Bilayer Graphene; Point defects; DFT simulations