Enhanced magnetocaloric properties in annealed Heusler Ni-Mn-Sn ribbons

In the present study, annealing effects on the magnetostructural transitions and magnetic properties were investigated based on Heusler Ni49Mn39Sn12 ribbons. Experimental results show that a larger magnetic entropy change is obtained in case of the ribbons annealed at 973 K. The enhancement was explained from the atomic order, thermal hysteresis and sub-grain microstructure. It is proposed that effective annealing occurs around the L21→B2 ordering transition temperature for Heusler Ni-Mn based ribbons.