Magnetoresistive Properties of Co2MnSi Heusler Alloy Films

Abstract

Co2MnSi thin films were prepared on SOI wafers by using Co/Mn metal deposition and rapid thermal annealing at 650 degrees C for 5 min in a high vacuum. The magnetoresistance (MR) of the Co2MnSi thin films was investigated in the temperature range from 50 to 300 K, and the MR behavior changed as magnetic field was increased. The MR(H) curves was divided into two parts: In the high-magnetic-field region, the MR, varied linearly with the magnetic field. At low magnetic fields, however, the MR changed nonlinearly with the magnetic field and was strongly temperature-dependent. This behavior is similar to the MR response of polycrystalline colossal magnetoresistive manganite. By using a phenomenological model to fit the experimental data, we found that at high fields, the MR was dominated by intragrain scattering due to spin fluctuations while at low fields, the MR was governed by intergrain scattering due to spin-polarized tunneling.