Modified Curie-Weiss Law for $j_{\rm eff}$ Magnets

TL;DR

This paper introduces a modified Curie-Weiss law tailored for spin-orbit-coupled magnetic materials, improving the analysis of susceptibility data and resolving discrepancies in magnetic coupling estimates.

Contribution

The authors propose a new Curie-Weiss formula that accounts for temperature-dependent local moments, enhancing the accuracy of magnetic parameter extraction in $j_{eff}$ magnets.

Findings

Modified formula aligns well with microscopic exchange calculations.

Reanalysis clarifies magnetic coupling magnitudes and anisotropies.

Resolves previous experimental discrepancies.

Abstract

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 $d^5$ 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.