Magnetostructural transitions and adiabatic temperature variation in polycrystal and single-crystal Ni2MnGa alloys

The magnetocaloric response of off-stoichiometric Ni2MnGa polycrystal and single-crystal samples with a Curie temperature coincident with the martensitic transition temperature was investigated. The direct measurement of temperature change (ΔTad) during an adiabatic transformation under a maximum field variation ΔH=5.6×106A∕m (7T) was performed. The polycrystalline sample shows a maximum ΔTad≈1.5K at a temperature close to the structural transition. The value of ΔTad and the 20K span of the ΔTad peak encourage further studies of the effect of microstructure on the magnetocaloric response of Ni2MnGa.