GdFe$_2$ Laves phase intermetallic system under pressure: an ab-initio study

TL;DR

This study uses ab-initio calculations to analyze how hydrostatic pressure affects the Curie temperature of GdFe₂, revealing the significant role of Fe-Gd exchange interactions in magnetic behavior.

Contribution

It provides a detailed ab-initio analysis of pressure effects on GdFe₂'s Curie temperature, highlighting the importance of Fe-Gd exchange interactions for the first time.

Findings

Curie temperature increases with pressure up to 70 Kbar.

Fe ions contribute about 75% to the experimental Curie temperature.

Fe-Gd exchange interactions account for the remaining 25%.

Abstract

Here we perform $ab-initio$ study of Curie temperature $T_C$ under hydrostatic pressure for intermetallic compound GdFe$_2$. To calculate $T_C$ for GdFe$_2$ we applied mean-field solution of the Heisenberg model for several magnetic sublattices with DFT/LDA calculated values of necessary exchange interaction integrals and local magnetic moments. To compare with available experimental data pressure values were taken from zero up to about 70 Kbar. It corresponds to 2\% compression of the volume of the unit cell. In agreement with experimental data $T_C$ grows under pressure. It was shown that Fe ions magnetic sublattice alone provides only about 75\% of the experimental Curie temperature $T_C^{exp}$. Gd sublattice is found to give very weak contribution to the $T_C^{exp}$. Here we show that the missing 25 \% of $T_C^{exp}$ comes from Fe-Gd exchange pairs.