Magnetic properties of thin epitaxial Pd$_{1-x}$Fe$_x$ alloy films

TL;DR

This study investigates the magnetic properties of epitaxial Pd-Fe alloy films, revealing tunable ferromagnetism, magnetic anisotropy, and coherent magnetic behavior, with implications for superconducting spintronics applications.

Contribution

It provides detailed experimental characterization and modeling of magnetic anisotropy and behavior in Pd-Fe alloy films, expanding understanding of dilute magnetic alloys.

Findings

Ferromagnetism is tunable by composition in Pd-Fe films.

In-plane magnetic anisotropy has four-fold symmetry with <110> easy axes.

Magnetic hysteresis can be modeled by the Stoner-Wohlfarth model.

Abstract

In the paper we present the results of extensive studies of palladium-rich Pd1-xFex alloy films epitaxially grown on MgO single-crystal substrate. In a composition range of x = 0.01-0.07 these materials are soft ferromagnets, the saturation magnetization and magnetic anisotropy of which can be tuned by its composition. Vibrating sample magnetometry was used to study temperature dependences of spontaneous magnetic moment and to establish the temperature of magnetic ordering (Curie temperature). Ferromagnetic resonance (FMR) measurements at low temperatures in the in-plane and out-of-plane geometries revealed the four-fold in-plane magnetic anisotropy with the easy directions along the <110> axes of the substrate. The modelling of the angular dependence of the field for resonance allowed to extract the cubic and tetragonal contributions to the magnetic anisotropy of the films and establish their dependence on the concentration of iron in the alloy. Experimental data are discussed in the framework of existing theories of dilute magnetic alloys. Using the anisotropy constants established from FMR, the magnetic hysteresis loops are reproduced utilizing the Stoner-Wohlfarth model thus indicating the predominant coherent magnetic moment rotation at low temperatures. The obtained results compile a database of magnetic properties of a palladium-iron alloy considered as a material for superconducting spintronics.