Exploration of all-3d Heusler alloys for permanent magnets: an ab initio based high-throughput study

TL;DR

This study uses high-throughput ab initio calculations to identify all-3d Heusler alloys with potential as permanent magnets, focusing on their magnetic properties, anisotropy, and temperature stability.

Contribution

The paper introduces a comprehensive high-throughput computational approach to discover and analyze all-3d Heusler alloys as promising permanent magnet materials.

Findings

Fe₂NiZn, Fe₂NiTi, and Ni₂CoFe are promising permanent magnet candidates.

These alloys exhibit large out-of-plane magnetic anisotropy and high Curie temperatures.

Strain significantly influences the magnetic anisotropy, enabling tunability.

Abstract

Heusler alloys have attracted interest in various fields of functional materials since their properties can quite easily be tuned by composition. Here, we have investigated the relatively new class of all-3d Heusler alloys in view of its potential as permanent magnets. To identify suitable candidates, we performed a high-throughput study using an electronic structure database to search for X$_2$YZ-type Heusler systems with tetragonal symmetry and high magnetization. For the alloys which passed our selection filters, we have used a combination of density functional theory calculations and spin dynamics modelling to investigate their magnetic properties including the magnetocrystalline anisotropy energy and exchange interactions. The candidates which fulfilled all the search criteria served as input for the investigation of the temperature dependence of the magnetization and determination of Curie temperature. Based on our results, we suggest that Fe$_2$NiZn, Fe$_2$NiTi and Ni$_2$CoFe are potential candidates for permanent magnets with large out-of-plane magnetic anisotropy (1.23, 0.97 and 0.82 MJ/m$^3$ respectively) and high Curie temperatures lying more than 200 K above the room temperature. We further show that the magnitude and direction of anisotropy is very sensitive to the strain by calculating the values of anisotropy energy for several tetragonal phases. Thus, application of strain can be used to tune the anisotropy in these compounds.