Magnetocaloric effect in Ni2MnxFeyInz Heusler alloys with second-order phase transition

The structural, magnetic, and magnetocaloric properties of Ni2MnxFeyInz with x + y + z = 2 alloys have been studied for the potential application in environment-friendly magnetic refrigeration technology. Samples were prepared using arc-melting and vacuum annealing techniques. Among the investigated materials, Ni2Mn1.32Fe0.08In0.60 possesses the highest value of entropy change with the Curie temperature close to room temperature (Tc = 315 K). The room temperature x-ray diffraction shows that the Ni2Mn1.32Fe0.08In0.60 alloy exhibits a cubic L21 structure (austenite phase) without any impurities. The isothermal magnetization curves show almost zero hysteresis with a high-field (μ0H = 3 T) magnetization at 100 K of 132 emu/g. The magnetic entropy change and relative cooling power measured at 3 T are 4.5 Jkg-1K-1 and 221 Jkg-1, respectively. The absence of thermal and magnetic hysteresis, relatively high values of magnetic entropy change and relative cooling power, and the Tc near room temperature suggest that the Ni2Mn1.32Fe0.08In0.60 alloy has a high potential for room-temperature magnetic refrigeration application.