# Berlin 2024 – wissenschaftliches Programm

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# HL: Fachverband Halbleiterphysik

## HL 24: Graphene and 2D Materials (joint session TT/HL)

### HL 24.4: Vortrag

### Mittwoch, 20. März 2024, 10:15–10:30, H 3007

Solitons induced by an in-plane magnetic field in rhombohedral multilayer graphene — •Max Tymczyszyn, Peter Cross, and Edward McCann — Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom

The low-energy band structure of rhombohedral graphene multilayers includes a pair of flat bands near zero energy, which are localized on the surface layers of a finite thin film. Introducing an in-plane magnetic field we find that the zero-energy bands persist, and that level bifurcations occur at energies determined by the component of the in-plane wave vector that is parallel to the external field. The occurrence of level bifurcations is explained by invoking semiclassical quantization of the zero-field Fermi surface of rhombohedral graphite. We find parameter regions with a single isoenergetic contour of Berry phase zero corresponding to a conventional Landau level spectrum and regions with two isoenergetic contours, each of Berry phase π, corresponding to a Dirac-like spectrum of levels. We write down an analogous one-dimensional tight-binding model and relate the persistence of the zero-energy bands in large magnetic fields to a soliton texture supporting zero-energy states in the Su-Schrieffer-Heeger model. We show that different states contributing to the zero-energy flat bands in rhombohedral graphene multilayers in a large field are localized on different bulk layers of the system, not just the surfaces.

[1] M. Tymczyszyn, P.H. Cross, E. McCann, Phys. Rev. B 108 (2023) 115425