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Spin-orbit coupling controlled two-dimensional magnetism in chromium trihalides

Inhee Lee1,*, Jiefu Cen2, Oleksandr Molchanov1, Shi Feng1, Warren L. Huey3, Johan van Tol4, Joshua E. Goldberger3, Nandini Trivedi1, Hae-Young Kee2,5 et al.

P. Chris Hammel1,†

  • *Contact author: lee.2338@osu.edu
  • †Contact author: hammel@physics.osu.edu
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Phys. Rev. B 113, 014401 – Published 5 January, 2026

DOI: https://doi.org/10.1103/qg64-ztxj

Abstract

CrX3 (X = Cl, Br, I) have the same crystal structure and Hamiltonian but different ligand spin-orbit coupling (SOC) constant λX, providing an excellent material platform exploring for exotic two-dimensional (2D) spin orders. Their microscopic mechanism underlying 2D spin physics remain unestablished, along with experimental corroboration of Kitaev exchange interaction, central to realizing topological quantum spin liquids. Finding direct evidence for Kitaev interaction and determining its value has been an essential but formidable challenge in Kitaev physics. Here we report the direct Kitaev interaction signature in magnetic anisotropy measured by ferromagnetic resonance (FMR) spectroscopy. We present measured values of Heisenberg J, Kitaev K, and off-diagonal symmetric Γ exchange interactions in CrX3 determined using FMR and exact diagonalization. K and Γ exhibit dominant dependencies on λX, indicating its central role in 2D magnetism. Our study provides a foundation for designing 2D magnetic materials exhibiting novel behaviors by tuning intrinsic material parameters such as SOC.

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Phys. Rev. B 113, 014401– Published 5 January, 2026
  • Received 17 July 2024
  • Revised 4 December 2025
  • Accepted 8 December 2025
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