Trigonal distortion in the Kitaev candidate honeycomb magnet BaCo2(AsO4)2

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Hauptverfasser: Ferreira-Carvalho, M. M., Rößler, S., Chang, C. F., Hu, Z., Valvidares, S. M., Gargiani, P., Haverkort, M. W., Mukharjee, Prashanta K., Gegenwart, P., Tsirlin, A. A., Tjeng, L. H.
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Veröffentlicht: 2025
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author Ferreira-Carvalho, M. M.
Rößler, S.
Chang, C. F.
Hu, Z.
Valvidares, S. M.
Gargiani, P.
Haverkort, M. W.
Mukharjee, Prashanta K.
Gegenwart, P.
Tsirlin, A. A.
Tjeng, L. H.
author_facet Ferreira-Carvalho, M. M.
Rößler, S.
Chang, C. F.
Hu, Z.
Valvidares, S. M.
Gargiani, P.
Haverkort, M. W.
Mukharjee, Prashanta K.
Gegenwart, P.
Tsirlin, A. A.
Tjeng, L. H.
contents We conducted x-ray absorption (XAS) and magnetic circular dichroism (XMCD) measurements at the Co $L_{2,3}$ edges on single crystals of the Kitaev candidate honeycomb lattice compound BaCo$_2$(AsO$_4$)$_2$. The measurements employed the inverse partial fluorescence yield technique, which is ideal for acquiring reliable x-ray absorption spectra from highly insulating samples, enabling precise quantitative analysis. Our experimental results revealed a significant linear dichroic signal, indicating strong trigonal distortion in the CoO$_{6}$ octahedra in BaCo$_2$(AsO$_4$)$_2$. We performed a detailed analysis of the experimental XAS and XMCD spectra using a full-multiplet configuration-interaction cluster model. This analysis unveiled that the $t_{2g}$ hole density is predominantly localized in the $a_{1g}$ orbital. Through XMCD sum rules and theoretical calculations, we quantified both the spin and orbital magnetic moments. Our study demonstrates that the local electronic structure of the CoO$_{6}$ octahedra displays an effective trigonal distortion of approximately $-0.114$ eV. This distortion is larger than the Co $3d$ spin-orbit coupling constant, emphasizing the crucial impact of local structural distortions on the electronic and magnetic properties of BaCo$_2$(AsO$_4$)$_2$.
format Preprint
id arxiv_https___arxiv_org_abs_2509_06746
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Trigonal distortion in the Kitaev candidate honeycomb magnet BaCo2(AsO4)2
Ferreira-Carvalho, M. M.
Rößler, S.
Chang, C. F.
Hu, Z.
Valvidares, S. M.
Gargiani, P.
Haverkort, M. W.
Mukharjee, Prashanta K.
Gegenwart, P.
Tsirlin, A. A.
Tjeng, L. H.
Strongly Correlated Electrons
We conducted x-ray absorption (XAS) and magnetic circular dichroism (XMCD) measurements at the Co $L_{2,3}$ edges on single crystals of the Kitaev candidate honeycomb lattice compound BaCo$_2$(AsO$_4$)$_2$. The measurements employed the inverse partial fluorescence yield technique, which is ideal for acquiring reliable x-ray absorption spectra from highly insulating samples, enabling precise quantitative analysis. Our experimental results revealed a significant linear dichroic signal, indicating strong trigonal distortion in the CoO$_{6}$ octahedra in BaCo$_2$(AsO$_4$)$_2$. We performed a detailed analysis of the experimental XAS and XMCD spectra using a full-multiplet configuration-interaction cluster model. This analysis unveiled that the $t_{2g}$ hole density is predominantly localized in the $a_{1g}$ orbital. Through XMCD sum rules and theoretical calculations, we quantified both the spin and orbital magnetic moments. Our study demonstrates that the local electronic structure of the CoO$_{6}$ octahedra displays an effective trigonal distortion of approximately $-0.114$ eV. This distortion is larger than the Co $3d$ spin-orbit coupling constant, emphasizing the crucial impact of local structural distortions on the electronic and magnetic properties of BaCo$_2$(AsO$_4$)$_2$.
title Trigonal distortion in the Kitaev candidate honeycomb magnet BaCo2(AsO4)2
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2509.06746