Single-Phase L1$_{0}$-Ordered High Entropy Thin Films with High Magnetic Anisotropy

TL;DR

This study demonstrates that rapid thermal annealing of high entropy alloy thin films can induce a single L1$_{0}$-ordered phase with high magnetic anisotropy, offering a new route for rare-earth-free magnetic materials.

Contribution

It introduces a method to achieve high magnetic anisotropy in HEA thin films through RTA-induced ordering, specifically forming an L1$_{0}$ phase with enhanced magnetic properties.

Findings

RTA increases coercivity by 40 times in HEA films.

Inclusion of Pt induces L1$_{0}$ ordering and high magnetic anisotropy.

HEA films can be engineered for high magnetic anisotropy without rare-earth elements.

Abstract

The vast high entropy alloy (HEA) composition space is promising for discovery of new material phases with unique properties. We explore the potential to achieve rare-earth-free high magnetic anisotropy materials in single-phase HEA thin films. Thin films of FeCoNiMnCu sputtered on thermally oxidized Si/SiO$_{2}$ substrates at room temperature are magnetically soft, with a coercivity on the order of 10 Oe. After post-deposition rapid thermal annealing (RTA), the films exhibit a single face-centered-cubic phase, with an almost 40-fold increase in coercivity. Inclusion of 50 at.% Pt in the film leads to ordering of a single L1$_{0}$ high entropy intermetallic phase after RTA, along with high magnetic anisotropy and 3 orders of magnitude coercivity increase. These results demonstrate a promising HEA approach to achieve high magnetic anisotropy materials using RTA.