Magnetoresistance and transformation hysteresis in the Ni 50Mn34.4In15.6 metamagnetic shape memory alloy

Abstract

Temperature dependence of the equilibrium transformation field (H 0) for Ni50Mn34.4In15.6 metamagnetic shape memory alloy was precisely determined by electrical resistivity measurements using a pulsed magnet. The H0-T curve was found to exhibit a maximum at around 50 K, suggesting that the transformation entropy change becomes negative in the lower temperature region. The residual electrical resistivity in the field-induced parent phase at lower temperatures was about 10 × 10-8 Ω·m, being normal value as the ferromagnetic alloys, whereas that in the martensite phase was high of about 200 × 10-8 Ω·m. The temperature dependence of the magnetic field hysteresis can be well fitted with the Seeger's theory proposed for plastic deformation by dislocations. © 2013 The Japan Institute of Metals.