Magnetoresistive properties of Co2MnSi Heusler alloy films

초록

Co2MnSi thin films were prepared on the SOI wafer by Co/Mn metal deposition and the rapid thermal annealing (RTA) at 650 oC for 5 mins in a high vacuum. The magnetoresistance (MR) of the Co2MnSi thin film was investigated in the temperature range from 50 to 300K, where the MR behavior changes as magnetic field increases. In the high magnetic field regime, the MR varies linearly with magnetic field. At low magnetic field, however, the MR changes nonlinearly with magnetic field and is strongly temperature-dependent. This behavior is similar to the magnetoresistance behavior of polycrystalline CMR manganite. By using a phenomenological model[1] for granular CMR materials to fit experimental data, we found out that the MR is dominated by the intragrain scattering due to the spin fluctuation in high field regime while the MR at low fields is dominated by the intergrain scattering due to the spin polarized tunneling.