In the field of magnetocaloric materials we follow a most recent trend where, due to their remarkable properties, Ni2MnX (X = Ga, In, Sn) based Heusler alloys are often considered as promising prototypical materials for magnetic refrigeration
We study the coincidence of martensitic transition with the magnetic transitions by the synthesis off-stoichiometric variation of the alloy composition around the Mn-rich composition - Ni50-xCoxMn30Ga20. Here the saturation magnetization of austenite is strongly enhanced by Co with respect to the martensitic one (contrary to the Co-free alloys) and thus MCE turns from direct into inverse, i.e. a cooling is induced by a putting of the alloy into external magnetic field and vice versa. By varying the composition, it is possible to tune the critical temperatures of martensitic transitions and the saturation magnetization jumps accompanied structural transitions. The remarkable values of the magnetic properties related to MCE, i.e. the high saturation magnetization jumps, the strong magnetic field and pressure dependence of the transformation temperature, can be often detected.
Direct measurement of magnetocaloric temperature change obtained in different magnetic field during magnetization and demagnetization of the Ni1.92Mn1.56Sn0.52 sample.