In spin-orbit-coupled magnetic materials, the usually applied Curie-Weiss law can break down. This is due to potentially sharp temperature-dependence of the local magnetic moments. We therefore propose a modified Curie-Weiss formula suitable for analysis of experimental susceptibility. We show for octahedrally coordinated materials of d5 filling that the Weiss constant obtained from the improved formula is in excellent agreement with the calculated Weiss constant from microscopic exchange interactions. Reanalyzing the measured susceptibility of several Kitaev candidate materials with the modified formula resolves apparent discrepancies between various experiments regarding the magnitude and anisotropies of the underlying magnetic couplings.
@article{arxiv.2102.08964,
title = {Modified Curie-Weiss Law for $j_{\rm eff}$ Magnets},
author = {Ying Li and Stephen M. Winter and David A. S. Kaib and Kira Riedl and Roser Valenti},
journal= {arXiv preprint arXiv:2102.08964},
year = {2021}
}