Regensburg 2025 – scientific programme
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MA: Fachverband Magnetismus
MA 40: Frustrated Magnets II
MA 40.5: Talk
Thursday, March 20, 2025, 16:00–16:15, H20
Trigonal distortion in the Kitaev candidate honeycomb magnet BaCo2(AsO4)2 — •M.M. Ferreira Carvalho1,2, S. Roessler1, Z. Hu1, C.F. Chang1, S. M. Valvidares3, P. Gargiani3, M. W. Haverkort4, P. K. Mukharjee5, P. Gegenwart5, A. A. Tsirlin6, and L.H. Tjeng1 — 1Max Planck Institute for Chemical Physics of Solids,Dresden — 2Institute of Physics II, University of Cologne — 3ALBA Synchrotron Light Source, Barcelona, Spain — 4Institute for theoretical physics, Heidelberg University — 5Lehrstuhl für Experimentalphysik VI, Universität Augsburg — 6Felix Bloch Institute for Solid-State Physics, University of Leipzig
We conducted X-ray linear dichroism (XLD) and magnetic circular dichroism (XMCD) measurements on single crystals of the Kitaev candidate honeycomb lattice compound BaCo2(AsO4)2. The measurements employed the bulk sensitive 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 LD signal, indicating strong trigonal distortion in the CoO6 octahedra in BaCo2(AsO4)2. We performed a detailed analysis of the experimental XAS and XMCD spectra using a full-multiplet cluster model within the configuration interaction approach. This analysis indicated that the hole density is predominantly localized in the a1g orbital. Through XMCD sum rules and theoretical calculations, we quantified both the spin and orbital magnetic moments.
Keywords: X-Ray Absorption Spectroscopy; Kitaev Quantum Spin Liquid; Frustrated Magnetism; X-Ray Magnetic Circular Dichroism