Berlin 2024 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 23: Topological Insulators and Weyl Semimetals (joint session MA/TT)
TT 23.8: Vortrag
Dienstag, 19. März 2024, 11:30–11:45, H 2013
Electrical Activity of Topological Chiral Edge Magnons — •Robin R. Neumann1, Alexander Mook2, Jürgen Henk1, and Ingrid Mertig1 — 1Martin Luther University Halle-Wittenberg, Halle (Saale), Germany — 2Johannes Gutenberg University, Mainz, Germany
Magnons, the bosonic quasiparticles of spin waves, have been predicted to feature similar topological phases as electrons. In particular, the topological band structure of the quantum Hall systems has its magnonic analogue in the topological magnon insulator (TMI), which hosts topologically protected chiral edge excitations. Beyond theoretical studies, however, there exist no direct experimental evidence of their existence as the lack of charge renders them invisible to most surface-sensitive probes.
In this talk I demonstrate how magnetoelectric coupling imparts an electric dipole moment to the chiral magnons that manifests in equilibrium and nonequilibrium. Considering a two-dimensional ferromagnetic TMI, an electric edge polarization perpendicular to the sample's edges is driven by thermal fluctuations of the collinear magnetic ground state in equilibrium. On the other hand, the TMI features a unique in-gap resonance in its electrical absorption spectrum that stems from the chiral magnons showcasing their electrical activity. These results suggest THz spectroscopy as promising probe for topological magnons.
Keywords: Magnons; Topology; Magnetelectric Coupling; Electric Polarization; Electric Absorption