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MA: Fachverband Magnetismus
MA 23: Cooperative Phenomena: Spin Structures and Magnetic Phase Transitions (joint session MA/TT)
MA 23.2: Vortrag
Dienstag, 10. März 2026, 14:15–14:30, POT/0151
Large magnetoreflectance and optical anisotropy due to 4f flat bands in the frustrated kagome magnet HoAgGe — •Felix Schilberth1,2, Luke DeFreitas3, Khan Zhao4,5, Florian Le Mardelé6, Ivan Mohelsky6, Milan Orlita6, Philipp Gegenwart5, Hua Chen3, István Kézsmárki1, and Sándor Bordács2 — 1Experimentalphysik V, Unversity of Augsburg — 2Department of Physics, BME Budapest — 3Department of Physics, Colorado State University — 4School of Physics, Beihang University — 5Experimentalphysik VI, Unversity of Augsburg — 6LNCMI, Université Grenoble Alpes
We report peculiar optical properties of the frustrated itinerant magnet HoAgGe, which exhibits multiple magnetically ordered states obeying the kagome spin-ice rule. The optical conductivity is higher for light polarization perpendicular to the kagome plane both for the free carrier response and the interband transitions. The latter have strong contributions from Ho 4f flat bands located near the Fermi level, as revealed by our ab initio calculations, explaining the unusual anisotropy of the optical properties and the pronounced temperature dependence of the interband transitions for out-of-plane light polarization. The key role of Ho 4f states is further supported by the large variation of the magneto-reflectivity, following the field dependence of the magnetization in contrast to that of the magnetotransport data. Such heavy-electron bands near the Fermi level offer an efficient way to control transport and optical properties and we show that their ultrafast magneto-optical response is susceptible to the magnetic order.
Keywords: Non-collinear Antiferromagnets; Magneto-Optics; Metamagnetic Phases; 4f Electrons; HoAgGe