Magnetic properties and magnetocaloric effect of Ni2Mn1+x-Sn1-x Heusler alloy thin films.

摘要

Ternary Heusler alloys defined as the stoichiometric composition X₂YZ with the L2₁ structure have attracted considerable attention due to their valuable transport and magnetic features. These compounds exhibit half-metallic behavior, magnetoresistance, magnetocaloric, shape memory and thermoelectric effects. The Heusler alloys Ni₂MnGa and off-stoichiometric Ni₂Mn_1+xZ_1-x (where Z = In, Sn and Sb) are typical examples of the ferromagnetic shape memory alloys due to physical phenomena such as the large magnetic field induced strain [1], the giant magnetocaloric effects [2]and the giant magnetoresistance [3]. Especially, Ni-Mn-X (where X = Ga, In, Sn) based magnetic shape memory alloys have been proposed as solid state energy efficient refrigerant with their remarkable first order transition feature [4-8]. Most of the magnetic refrigeration materials have been studied in bulk sample. However, by changing the sample shape, it is expected to realize the efficient heat exchange and the downsized cooling device. In this study, in order to evaluate the influence on magnetic properties and magnetocarolic effect due to substrate material, heat treatment temperature and composition in Ni₂Mn_1+xSn_1-x Heusler films were investigated.