Large magnetoreflectance and optical anisotropy due to $4f$ flat bands in the frustrated kagome magnet HoAgGe

Fuente: arXiv
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Main Authors: Schilberth, F., DeFreitas, L., Zhao, K., LeMardelé, F., Mohelsky, I., Orlita, M., Gegenwart, P., Chen, H., Kézsmárki, I., Bordács, S.
Format: Preprint
Published: 2025
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author Schilberth, F.
DeFreitas, L.
Zhao, K.
LeMardelé, F.
Mohelsky, I.
Orlita, M.
Gegenwart, P.
Chen, H.
Kézsmárki, I.
Bordács, S.
author_facet Schilberth, F.
DeFreitas, L.
Zhao, K.
LeMardelé, F.
Mohelsky, I.
Orlita, M.
Gegenwart, P.
Chen, H.
Kézsmárki, I.
Bordács, S.
contents 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 surprisingly higher for light polarization perpendicular to the kagome plane, both for the free carrier response and the interband transitions. The latter ones have strong contributions from Ho $4f$ flat bands located near the Fermi level, as revealed by our \textit{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 reflectivity upon the metamagnetic transitions, that follows the field dependence of the magnetization, in contrast to that of the dc magnetotransport data. Such heavy-electron bands near the Fermi level offer an efficient way to control transport and optical properties.
format Preprint
id arxiv_https___arxiv_org_abs_2504_10274
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Large magnetoreflectance and optical anisotropy due to $4f$ flat bands in the frustrated kagome magnet HoAgGe
Schilberth, F.
DeFreitas, L.
Zhao, K.
LeMardelé, F.
Mohelsky, I.
Orlita, M.
Gegenwart, P.
Chen, H.
Kézsmárki, I.
Bordács, S.
Strongly Correlated Electrons
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 surprisingly higher for light polarization perpendicular to the kagome plane, both for the free carrier response and the interband transitions. The latter ones have strong contributions from Ho $4f$ flat bands located near the Fermi level, as revealed by our \textit{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 reflectivity upon the metamagnetic transitions, that follows the field dependence of the magnetization, in contrast to that of the dc magnetotransport data. Such heavy-electron bands near the Fermi level offer an efficient way to control transport and optical properties.
title Large magnetoreflectance and optical anisotropy due to $4f$ flat bands in the frustrated kagome magnet HoAgGe
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2504.10274