LAUSR

We present a comparison study of the temperature dependence of the intriguing magnetoresistance (MR) in Pt/YIG (yttrium iron garnet), Pt/YIGBB (the YIG substrate has been bombarded with Ar+), and Pt/SiO2 (with different Fe doping levels). With decreasing temperature, the MRs in Pt/YIG and Pt/YIGBB change symmetry from Rz = Rx > Ry at room temperature to Rx > Rz > Ry at low temperature. A similar behavior in both Pt/YIG and Pt/YIGBB implies that the underlying physics is due to magnetic scattering, instead of the pure spin current across the interface. By changing the Fe doping level in the SiO2 substrate, we can further systematically modulate the symmetry of MR in Pt/SiO2 (Fe doped). The doping level dependent symmetry can also qualitatively explain the controversy over the MRs of Pt/YIG and similar structures at low temperature.