Spin relaxation characteristics in Ag nanowire covered with various oxides

摘要

We have studied spin relaxation characteristics in a Ag nanowire covered with various oxide layers of Bi_2O_3, Al_2O_3, HfO_2, MgO, or AgO_x by using non-local spin valve structures. The spin-flip probability, a ratio of momentum relaxation time to spin relaxation time at 10K, exhibits a gradual increase with an atomic number of the oxide constituent elements, Mg, Al, Ag, and Hf. Surprisingly, the Bi_2O_3 capping was found to increase the probability by an order of magnitude compared with other oxide layers. This finding suggests the presence of an additional spin relaxation mechanism such as Rashba effect at the Ag/Bi_2O_3 interface, which cannot be explained by the simple Elliott-Yafet mechanism via phonon, impurity, and surface scatterings. The Ag/Bi_2O_3 interface may provide functionality as a spin to charge interconversion layer.