Field-induced magnetic transitions in the highly anisotropic ferrimagnet ErFe5Al7 studied by high-field x-ray magnetic dichroism

We present a comprehensive study of the magnetic properties of the strongly anisotropic ferrimagnet ErFe₅Al₇ in pulsed magnetic fields up to 30 T applied along the hard magnetization axis within the basal plane of the tetragonal lattice around the compensation temperature (Tcomp). Macroscopic measurements showed two anomalies at about 8 T and 25 T in a small temperature range around Tcomp. High-field x-ray magnetic circular dichroism (XMCD) data at the Er M₅- and the Fe L₃-edge resonances provide insight into the element-selective magnetization processes, revealing a coherent rotation of Er $4f$ and Fe $3d$ moments, with stepwise jumps including an unexpected one from an easy to a hard magnetization axis. XMCD at the Er L₃-edge resonance elucidates the role of Er $5d$ electrons in coupling the Er $4f$ and the Fe $3d$ moments. Finally, an in-plane anisotropy constant was evaluated from a simulation of the magnetization process at temperatures well below Tcomp using a two-sublattice model.