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MM: Fachverband Metall- und Materialphysik
MM 25: Interface Controlled Properties, Nanomaterials, and Microstructure Design I
MM 25.4: Vortrag
Mittwoch, 11. März 2026, 16:30–16:45, SCH/A215
Non-Hermitian physics and exceptional points at Z2 Weyl semimetal*ferromagnet junctions — •Tong Wang1, Robert Amelung2, and Flore Kunst1,2 — 1Max Planck Institute for the Science of Light, Staudtstraße 2, 91058 Erlangen, Germany — 2Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
Non-Hermitian systems extend beyond the framework of Hermitian quantum mechanics and allow for the description of open systems with loss and gain. The study of non-Hermitian physics leads to an enrichment of topological phases of matter and practical applications in photonics and sensing. Here we study the junction between a metallic ferromagnet and a Z2 Weyl semimetal [1], where a combined time-reversal symmetry and reflection symmetry leads to degenerate helical Fermi arcs on certain surfaces. The couplings at the material interface give arise to a complex self-energy in the Green’s function [2], rendering the effective Hamiltonian of the Fermi arc surface states non-Hermitian. We show that non-Hermiticity can break a degenerate Fermi arc into pairs of exceptional point, and the resulting exceptional phase persists for a wide parameter range regarding the magnetization of the ferromagnet and topological mass term of the semimetal. We also discuss the how the exceptional points may influence physical properties of the Z2 Weyl semimetal. [1] T. Morimoto and A. Furusaki, Phys. Rev. B 89 235127 (2014). [2] E. J. Bergholtz and J. C. Budich, Phys. Rev. Res 1 012003(R) (2019).
Keywords: non-Hermitian physics; material junctions; topological semimetal; quantum transport; exceptional degeneracy