NCAFM2023 Programme Booklet

Wednesday 1440 - 1500

INVESTIGATION OF CORRELATED STATE IN BERNAL BILAYER GRAPHENE

Can Li1, Yufeng Liu1, Shiyong Wang *1

1 School of Physics and Astronomy, Shanghai Jiao Tong University, 200240, China Email: shiyong.wang@sjtu.edu.cn

In recent years, various phenomena such as correlated insulating states, spin-polarized superconductivity, and isospin magnetism have been observed in Bernal bilayer graphene systems [1-4]. However, there is currently no evidence suggesting the presence of symmetry-breaking correlated states in Bernal-stacked bilayer graphene at microscope. In this study, we utilized scanning tunnelling microscopy and spectroscopy to investigate high-quality Bernal-stacked bilayer graphene aligned with an h-BN substrate. By harnessing the effective electric field generated by the moiré potential, we observed a flattening of the band structure in Bernal bilayer graphene, indicating a high density of states at the Von Hove singularity. Upon partial filling of the flat band, we observed the opening of a correlated gap near the Fermi level, with the gap size increasing under an out-of-plane magnetic field. Our measurements under various magnetic fields provide evidence of Stoner ferromagnetism, indicating the existence of symmetry-breaking correlated states in Bernal bilayer graphene systems,

References [1] H. Zhou, L. Holleis, Y. Saito, et al., Science 2022;375(6582):774-778. [2] A. M. Seiler, F. R. Geisenhof, F. Winterer, et al., Nature. 2022;608(7922):298-302. [3] F. R. Geisenhof, F. Winterer, A. M. Seiler, et al., Nature. 2021;598(7879):53-58. [4] J. Velasco, L. Jing, W. Bao, et al., Nature Nanotech. 2012;7(3):156-160.

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