The large magnetocaloric effect and refrigerant capacity in nanocrystalline/ amorphous Gd$_3$Ni/Gd$_{65}$Ni$_{35}$ composite microwires

TL;DR

This study introduces nanocrystalline/amorphous Gd$_3$Ni/Gd$_{65}$Ni$_{35}$ composite microwires with enhanced magnetocaloric properties, showing significant potential for magnetic refrigeration near 120 K.

Contribution

It reports the creation and characterization of a novel nanocrystalline/amorphous composite microwire with superior magnetocaloric effects compared to bulk materials.

Findings

Large magnetic entropy change (~9.64 J/kg K) at 120 K

Refrigerant capacity (~742.1 J/kg) exceeds bulk counterparts

Enhanced magnetocaloric performance for magnetic refrigeration

Abstract

We report on a novel class of nanocrystalline/amorphous Gd$_3$Ni/Gd$_{65}$Ni$_{35}$ composite microwires, which was created directly by melt-extraction through controlled solidification. X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the formation of a biphase nanocrystalline/amorphous structure in these wires. Magnetic and magnetocaloric experiments indicate the large magnetic entropy change (-$\Delta$SM ~9.64 J/kg K) and the large refrigerant capacity (RC ~742.1 J/kg) around the Curie temperature of ~120 K for a field change of 5 T. These values are ~1.5 times larger relative to its bulk counterpart, and are superior to other candidate materials being considered for active magnetic refrigeration in the liquid nitrogen temperature range.