Large low-field inverse magnetocaloric effect near room temperature in Ni50-x Mn37+x In13 Heusler alloys

Low field inverse magnetocaloric effect (IMCE) associated with first-order martensitic transition in Ni50-x Mn37+x In-13 (x=3,4,5) alloys was investigated. By tuning the composition of Ni/Mn, large change in the magnetization occurring between martensite and austenite phases in a narrow temperature interval was achieved, which results in large IMCE. Under low magnetic field change of 2 T, a large positive magnetic entropy change (Delta S (M) ) of 23.5 J/kg K with a net refrigeration capacity of 53 J/kg was obtained near room temperature (308 K) in the x=3 alloy. The results show that a small variation in Ni/Mn ratio significantly influences the martensitic transition temperature and the associated magnetic and magnetocaloric properties.