Tuning the magnetoresistance symmetry of Pt on magnetic insulators with temperature and magnetic doping

摘要

We present a comparison study of the temperature dependence of the intriguing magnetoresistance (MR) in Pt/YIG (yttrium iron garnet), Pt/YIG_(BB) (the YIG substrate has been bombarded with Ar~+), and Pt/SiO_2 (with different Fe doping levels). With decreasing temperature, the MRs in Pt/YIG and Pt/YIGBB change symmetry from R_Z=R_X> R_y at room temperature to R_x>R_z>R_y at low temperature. A similar behavior in both Pt/YIG and Pt/YIG_(BB) 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 SiO_2 substrate, we can further systematically modulate the symmetry of MR in Pt/ SiO_2 (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.