On the structural and thermo-magnetic study of the magnetocaloric Heusler alloy Ni₂Mn_1-xCu_xGa_0.8Al_0.2

Full Heusler alloys present martensitic transition and shape memory effect related phenomena and several technological applications can be envisaged. One promising area is the magnetocaloric effect (MCE) as the magnetic and structural transitions combine to produce a large isothermal entropy and adiabatic temperature change useful for heating and cooling applications. In this work, we study a Ni–(Mn, Cu)–(Ga, Al) Heusler alloy family which has a giant MCE when the chemical composition is fine-tuned to bring the temperature of the second-order magnetic transition close the first-order structural one. Our results show that, for a certain range of copper concentration, the samples show interesting physical properties captured by calorimetric, microscopy imaging, and magnetization measurements, leading to a high MCE with minimized hysteresis. (paper)