Magneto-structural transitions and adiabatic temperature variation in poly-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 Tad during an adiabatic transformation under a maximum field variation H=5.6106 A/m 7 T was performed. The polycrystalline sample shows a maximum Tad1.5 K at a temperature close to the structural transition. The value of Tad and the 20 K span of the Tad peak encourage further studies of the effect of microstructure on the magnetocaloric response of Ni2MnGa.