Optical anisotropy of the kagome magnet FeSn: Dominant role of excitations between kagome and Sn layers

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Auteurs principaux: Ebad-Allah, J., Jiang, M. -C., Borkenhagen, R., Meggle, F., Prodan, L., Tsurkan, V., Schilberth, F., Guo, G. -Y., Arita, R., Kézsmárki, I., Kuntscher, C. A.
Format: Preprint
Publié: 2024
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author Ebad-Allah, J.
Jiang, M. -C.
Borkenhagen, R.
Meggle, F.
Prodan, L.
Tsurkan, V.
Schilberth, F.
Guo, G. -Y.
Arita, R.
Kézsmárki, I.
Kuntscher, C. A.
author_facet Ebad-Allah, J.
Jiang, M. -C.
Borkenhagen, R.
Meggle, F.
Prodan, L.
Tsurkan, V.
Schilberth, F.
Guo, G. -Y.
Arita, R.
Kézsmárki, I.
Kuntscher, C. A.
contents Antiferromagnetic FeSn is considered to be a close realization of the ideal two-dimensional (2D) kagome lattice, hosting Dirac cones, van Hove singularities, and flat bands, as it comprises Fe$_3$Sn kagome layers well separated by Sn buffer layers. We observe a pronounced optical anisotropy, with the low-energy optical conductivity being surprisingly higher perpendicular to the kagome planes than along the layers. This finding contradicts the prevalent picture of dominantly 2D electronic structure for FeSn. Our material-specific theory reproduces the measured conductivity spectra remarkarbly well. A site-specific decomposition of the optical response to individual excitation channels shows that the optical conductivity for polarizations both parallel and perpendicular to the kagome plane is dominated by interlayer transitions between kagome layers and adjacent Sn-based layers. Moreover, the matrix elements corresponding to these transitions are highly anisotropic, leading to larger out-of-plane conductivity. Our results evidence the crucial role of interstitial layers in charge dynamics even in seemingly 2D systems.
format Preprint
id arxiv_https___arxiv_org_abs_2404_12111
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Optical anisotropy of the kagome magnet FeSn: Dominant role of excitations between kagome and Sn layers
Ebad-Allah, J.
Jiang, M. -C.
Borkenhagen, R.
Meggle, F.
Prodan, L.
Tsurkan, V.
Schilberth, F.
Guo, G. -Y.
Arita, R.
Kézsmárki, I.
Kuntscher, C. A.
Materials Science
Antiferromagnetic FeSn is considered to be a close realization of the ideal two-dimensional (2D) kagome lattice, hosting Dirac cones, van Hove singularities, and flat bands, as it comprises Fe$_3$Sn kagome layers well separated by Sn buffer layers. We observe a pronounced optical anisotropy, with the low-energy optical conductivity being surprisingly higher perpendicular to the kagome planes than along the layers. This finding contradicts the prevalent picture of dominantly 2D electronic structure for FeSn. Our material-specific theory reproduces the measured conductivity spectra remarkarbly well. A site-specific decomposition of the optical response to individual excitation channels shows that the optical conductivity for polarizations both parallel and perpendicular to the kagome plane is dominated by interlayer transitions between kagome layers and adjacent Sn-based layers. Moreover, the matrix elements corresponding to these transitions are highly anisotropic, leading to larger out-of-plane conductivity. Our results evidence the crucial role of interstitial layers in charge dynamics even in seemingly 2D systems.
title Optical anisotropy of the kagome magnet FeSn: Dominant role of excitations between kagome and Sn layers
topic Materials Science
url https://arxiv.org/abs/2404.12111