Effect of structural disorder on the magnetocaloric properties of Ni-Mn-Sn alloy

The magnetic and magnetocaloric properties of Ni50Mn36.5Sn13.5 Heusler alloy has been studied by varying the duration of annealing (0, 6, 12, 18, and 24 h) at 1173 K. The atomic ordering increases, martensitic transition (MT) becomes sharper and exchange bias field increases with increasing annealing time. The sample annealed for 24 h has shown a large magnetic entropy change (Delta S-M) near its MT. But, the net refrigerant capacity at the MT of 12 h annealed sample is larger than the former one. We have discussed these results in the context of structural disorder and the ferro/antiferro correlations present in these alloy systems. (C) 2014 AIP Publishing LLC.