Thickness-dependent magnetism variation for ferrimagnetic rare-earth/transition metal films
Phys. Rev. Materials 9, 086001 – Published 14 August, 2025
DOI: https://doi.org/10.1103/18l1-7lcw
Abstract
The magnetic compensation effect in rare-earth/transition metal alloys, in which the magnetization of the antiferromagnetically aligned rare-earth and transition metal sublattices cancel each other out, can be utilized in a number of novel applications. However, nanoscale composition variations of the rare-earth/transition metal ratio broaden the temperature range of magnetic compensation (i.e., near zero net magnetization) and can even result in the reversal of the dominant magnetic sublattice at a given temperature. We observe a spin reorientation in sputter-grown thin films with nominal as a function of film thickness. Thicker films (> 50 nm thickness) exhibit an in-plane anisotropy near room temperature, while robust out-of-plane anisotropy is observed in thin films ( nm) at all temperatures. Correspondingly, the compensation temperature for thick films is near 25 K, while that for thin films is above room temperature. A film with intermediate thickness ( nm) displays a more complicated evolution of magnetic configurations. X-ray and polarized neutron scattering indicate that while structurally the intermediate thickness film appears homogeneous along the film normal direction, its depth-dependent magnetization profile is unusual, with two phases that have different compensation behavior. Elemental mapping using high-resolution electron microscopy reveals column formation leading to lateral variations in the Fe:Gd ratio near the top of the film, while Fe and Gd are uniformly distributed near the bottom of the layer. Our results identify an unexpected transitional thickness region in films where the nonuniform elemental distribution leads to complex multistep magnetization behavior that should be controlled or could be leveraged in spintronic and magneto-optical applications.
