Competing ferromagnetic and antiferromagnetic interactions drive the magnetocaloric tunability in Gd55Co30NixAl15-x microwires

TL;DR

This study investigates how competing ferromagnetic and antiferromagnetic interactions in Gd-Co-Ni-Al microwires influence their magnetic and magnetocaloric properties, enabling tunable refrigeration performance.

Contribution

It reveals the coexistence of FM and AFM interactions in Gd-based microwires and how their balance affects magnetocaloric tunability, a novel insight for magnetic refrigeration materials.

Findings

AFM interactions hinder long-range FM order.

Al dilution decreases Curie temperature.

Tuning interactions preserves refrigerant capacity.

Abstract

We have employed Gd55Co30NixAl15-x (x = 10, 5 and 0) amorphous microwires as a model system to unravel the impact of multiple magnetic interactions on the magnetism and the magnetocaloric behavior in Gd-alloy microwire systems. Our study shows that in addition to the RKKY ferromagnetic (FM) interaction (Gd-Gd), antiferromagnetic (AFM) interactions (Gd-Co, Gd-Ni) coexist and contribute to the magnetic and magnetocaloric response of the system. The dilution effect of Al element on the FM Gd-Gd interaction is responsible for the decrease of the Curie temperature (TC), whereas the increase of the saturation magnetization (MS) is originated from the reduced AFM Gd-Ni interaction. A thorough analysis of critical exponents suggests that the presence of the AFM interactions hinders the system to exhibit a long-range FM order below the TC. Adjusting these interactions is shown to preserve the large refrigerant capacity (RC) while tuning the TC over a wide temperature range, which is desirable for active magnetic refrigeration.