Magnetostructural transitions and adiabatic temperature variation in polycrystal and single-crystal Ni 2MnGa alloys

Abstract

The magnetocaloric response of off-stoichiometric Ni2 MnGa polycrystal and single-crystal samples with a Curie temperature coincident with the martensitic transition temperature was investigated. The direct measurement of temperature change (Δ Tad) during an adiabatic transformation under a maximum field variation ΔH=5.6× 106 Am (7 T) was performed. The polycrystalline sample shows a maximum Δ Tad ≈1.5 K at a temperature close to the structural transition. The value of Δ Tad and the 20 K span of the Δ Tad peak encourage further studies of the effect of microstructure on the magnetocaloric response of Ni2 MnGa. © 2006 American Institute of Physics.