Importance of anisotropic interactions for hard-axis or hard-plane ordering of Ce-based ferromagnets
Phys. Rev. B 112, 024437 – Published 25 July, 2025
DOI: https://doi.org/10.1103/99ww-msjh
Abstract
Ferromagnetic (FM) Kondo-lattice (KL) compounds often exhibit intriguing magnetic behavior driven by strong crystal electric field (CEF) anisotropy and exchange interactions. Recent studies suggest that many Ce- and Yb-based KL ferromagnets order along the hard-axis or hard-plane determined by their CEF ground state. We performed a survey of Ce-based FM compounds, complemented with new single-crystal synthesis, magnetization measurements, and analysis of the CEF scheme. Our results reveal that hard-axis or hard-plane ordering is less common than previously reported, with most compounds ordering along their easy-axis or easy-plane. We also find no clear correlation between the strength of the Kondo effect and whether a compound adopts hard-axis or hard-plane or easy-axis or easy-plane ordering. Instead, the key driver appears to be the competition between CEF anisotropy and exchange interaction anisotropy. A direct comparison of CeCuSi and further indicates that antiferromagnetic interactions along the CEF easy-axis can be crucial in stabilizing the hard-axis FM ordering observed in . Finally, our results suggest that an anisotropic Ruderman–Kittel–Kasuya–Yosida model could offer deeper insights into the complicated magnetic properties of Ce-based and other heavy-fermion systems.
