Effect of Si and Ga substitutions on the magnetocaloric properties of NiCoMnSb quaternary Heusler alloys

摘要

The effect of Si and Ga substitutions on the magnetic and the magnetocaloric properties in Heusler based system Ni_(46)Co_4Mn_(38)Sb_(12-x)Z_x (Z = Si and Ga) has been studied. From the M(T) plots it is found that Si substitution stabilizes the austenite phase, whereas Ga substitution stabilizes the martensite phase. Strong metamagnetic behavior is observed in the M(H) isotherms for Si = 0.75 and 1, whereas such a behavior is absent in the Ga substituted alloys. Associated with magneto-structural transition, a large magnetocaloric effect (MCE) of 58 and 70 J/kg K is observed for x = 0.75 and 1, respectively, in the case of Si. Though the MCE observed in x = 0.5 and 1 in the case of Ga is much lower, the MCE peak is found to be quite broad.