Direct Measurements of Magnetocaloric Effect in a Single Crystalline Ni<sub>2.13</sub>Mn<sub>0.81</sub>Ga<sub>1.06</sub> Heusler Alloy

Abstract

Magnetocaloric effect (MCE) in the vicinity of first order martensitic transformation and second order magnetic transition in a single crystalline Ni2.13Mn0.81Ga1.06 Heusler compound was studied by a direct method. The obtained results revealed that, for the applied magnetic field strength μ0H = 1.9 T, MCE is irreversible in the vicinity of the first order martensitic transformation only when the MCE measurements are performed under cooling protocol. Plot of the experimentally measured adiabatic temperature change ΔTad as a function of temperature T indicated that ΔTad has a negligible benefit from the magnetic field-induced conversion of the high-temperature austenitic phase into the low-temperature martensitic phase and is mainly determined by the paraprocess of the austenitic phase around both direct and reverse martensitic transformations.