Spin-polarized electron tunneling in polycrystalline Sr₂FeMoO₆ thin films

Abstract

We report a comparative study of magnetotransport in high quality epitaxial and polycrystalline thin films of Sr₂FeMoO₆ deposited on single crystal substrates of SrTiO₃ (STO) and Yttria-stabilized zirconia (YSZ) respectively. The polycrystallinity of the films on YSZ affects their magnetotransport significantly. The resistivity ρ(T) of such films is thermally activated in contrast to metallic behavior of ρ(T) of the thin films on STO. A large ( ≈13 %) low-field magnetoresistance (MR) at 10 K is seen in the polycrystalline samples compared to the negligibly small MR ( ≈2.5 %)of their epitaxial counterparts. A detail analysis of the temperature and magnetic-field-dependent resistivity and magnetization provide strong evidence for tunneling of spin-polarized carriers through a magnetic intergranular material of insulating ground state.