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Crystal fields and the properties of the Kitaev candidate Na3Co2SbO6 probed with x-ray absorption spectroscopy

M. M. Ferreira-Carvalho1,2, S. H. Chen1, Y. C. Ku3,4, S. Rößler1, Robert Kluge5, Ryan C. Morrow5, Javier Herrero-Martín6, P. Gargiani6, C. Y. Kuo3,4 et al.

C. F. Chang1, Alexander C. Komarek1, Z. Hu1, M. W. Haverkort7, and L. H. Tjeng1

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Phys. Rev. B 114, 175123 – Published 17 September, 2026

DOI: https://doi.org/10.1103/t8x5-t8bg

Abstract

We directly probe the local electronic structure and magnetic properties of Na3Co2SbO6 using x-ray absorption linear dichroism (XLD) and x-ray magnetic circular dichroism, complemented by full-multiplet cluster calculations. The Co L2,3-edge XLD spectra reveal significantly distorted CoO6 octahedra, which are quantitatively described by a low-symmetry cluster model incorporating Co-O covalency and orbital mixing. We identify a dominant trigonal crystal-field splitting of approximately −42.5meV, which drives the system away from the ideal Jeff=1/2 limit. We also demonstrate that a purely trigonal description is insufficient: small additional splittings of the egπ and egσ orbitals are essential to consistently reproduce the full set of experimental data, including the observed macroscopic in-plane magnetization anisotropy. Our results further establish Na3Co2SbO6 as a honeycomb cobaltate relevant to Kitaev quantum spin liquid physics, featuring a doubly degenerate ground state.

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Phys. Rev. B 114, 175123– Published 17 September, 2026
  • Received 22 May 2026
  • Revised 7 August 2026
  • Accepted 19 August 2026
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