Magnetocaloric Effect in ScGdHo Medium-Entropy Alloy

Abstract

The search for effective solid-state refrigerant for magnetocaloric application is one of the mainstream topics in materials science. Rare-earth multi-principal element alloys seem to be promising candidates for these purposes. In this study, we address the issues of structure formation, magnetic and magnetocaloric properties in ScGdHo medium entropy alloy. We perform the ab initio molecular dynamics simulations for the liquid and solid phases in this system and reveal a strong tendency to form a single-phase solid solution. The experimentally fabricated alloy demonstrates a single-phase HCP crystalline structure with high density of defects. The magnetic measurements reveal a complicated magnetic behavior in the material. The alloy exhibits antiferromagnetic or ferromagnetic behavior depending on the magnetic field. We have found that AFM order is preferable under a weak magnetic field and FM order occurs when the field strength exceeds 1.2 T. The alloy reveals a rather large coercive force in a wide temperature range up to the Neel point. The values of the magnetic entropy change and relative cooling power calculated for a magnetic field change of 0-5 T are 8.93 \(Jkg^{-1}K^{-1}\) and 938 J/kg, respectively. The examined ScGdHo alloy demonstrates the best magnetocaloric properties among similar rare-earth metal materials discovered to date.