Importance of anisotropic interactions for hard-axis/plane ordering of Ce-based ferromagnets

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-based 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/plane ordering is less common than previously reported, with most compounds ordering along their easy-axis/plane. We also find no clear correlation between the strength of the Kondo effect and whether a compound adopts hard-axis/plane or easy-axis/plane ordering. Instead, the key driver appears to be the competition between CEF anisotropy and exchange interaction anisotropy. A direct comparison of CeCuSi and CeAgSb${}_2$ further indicates that antiferromagnetic (AFM) interactions along the CEF easy-axis can be crucial in stabilizing the hard-axis FM ordering observed in CeAgSb${}_2$. Finally, our results suggest that an anisotropic Ruderman-Kittel-Kasuya-Yosida (RKKY) model could offer deeper insights into the complicated magnetic properties of Ce-based and other heavy-fermion systems.

Accepted by PRB

References in corpus (12)

• CeRuPO: A rare example of a Ferromagnetic Kondo lattice
• Multiple quantum phase transitions and superconductivity in Ce-based heavy fermions
• Bulk single crystal growth of the theoretically predicted magnetic Weyl semimetals $R$AlGe ($R$ = Pr, Ce)
• Single crystal growth and anisotropy of CeRuPO
• Ferromagnetism and superconductivity in P-doped CeFeAsO
• Kondo-lattice ferromagnets and their peculiar order along the magnetically hard axis
• Magnetic hard-axis ordering near ferromagnetic quantum criticality
• Investigation of the physical properties of the tetragonal CeMAl4Si2 (M = Rh, Ir, Pt) compounds
• Magnetic, thermodynamic, and magnetotransport properties of CeGaGe and PrGaGe single crystals
• Complex magnetism and strong electronic correlations in Ce2PdGe3
• Suppression of ferromagnetism governed by a critical lattice parameter in CeTiGe$\_3$ with hydrostatic pressure or V substitution
• Easy-plane ferromagnetic ordering and crystal-field ground state in the Kondo lattice CeCuSi