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 (ΔT_ad) during an adiabatic transformation under a maximum field variation ΔH=5.6×10⁶ A/m (7 T) was performed. The polycrystalline sample shows a maximum ΔT_ad≈1.5 K at a temperature close to the structural transition. The value of ΔT_ad and the 20 K span of the ΔT_ad peak encourage further studies of the effect of microstructure on the magnetocaloric response of Ni₂MnGa. [ABSTRACT FROM AUTHOR]