Large inverse magnetocaloric effect in Ni48.5−xCoxMn37Sn14.5 (x = 0, 1 and 2) with negligible hysteresis

Structural and magnetic transitions of Ni48.5−xCoxMn37Sn14.5 (x = 0, 1 and 2) alloys were studied by thermal, electrical and magnetic measurements. The exchange bias was found to be present in all the samples below 120 K. Contrary to other Heusler alloys, no magnetic hysteresis was observed in the isothermal M-H curves for x = 0 sample at the first order magneto-structural transition. Large magnetic entropy change (ΔSM) ∼ 6.15, 10.36 and 9.85 J/kg K was obtained respectively for x = 0, 1 and 2 due to a change of only 1.5 T magnetic field. Incorporating hysteresis losses, refrigerant capacity was estimated to be 50, 74 and 54.7 J/kg for the same samples respectively.