Evidence of Hysteresis Free Ferromagnetic Nature and Significant Magnetocaloric Parameters in FeNi Binary Alloy

In this study, our aim is to investigate the structural, magnetic, and magnetocaloric properties of the FeNi binary alloy. The FeNi alloy with Fe65Ni35 composition was prepared by ball milling followed by the annealing and quenching processes. A Rietveld refinement analysis of structural results reveals that this system has coexisting cubic structural phases with a dominant face-centered cubic phase (Fm-3m;γ-FeNi). Magnetization results of this compound indicate the presence of ferromagnetic ordering and the magnetic transition observed around 100 K. Moreover, an Arrott plot study provides information about the order of phase transition, which is found in the second-order near the ordering temperature, whereas first-order nature is also noted in the low-temperature region. The significant magnetocaloric parameters, i.e., magnetic entropy change (ΔSM~0.495 J/kg-K) and relative cooling power (88 J/kg), are noted over a wide temperature range. The power law dependency of magnetic entropy change with the applied field is also investigated. Due to their significant magnetocaloric performance over a wide temperature range, these multiphase alloys may be a good candidate for room-temperature to low-temperature magnetic refrigeration.