Thermal stability of the spin injection in Co/Ag/Co lateral spin valves

Spin injection, spin diffusion, and spin detection are investigated in Co/Ag/Co lateral spin valves at room temperature. Clear spin accumulation signals are detected by the non-local measurement. By fitting the results to the one-dimensional diffusion equation, similar to 8.6% spin polarization of the Co/Ag interface and similar to 180 nm spin diffusion length in Ag are obtained. Thermal treatment results show that the spin accumulation signal drastically decreases after 100 degrees C annealing, and disappears under 200 degrees C annealing. Our results demonstrate that, compared to the spin diffusion length, the decrease and the disappearance of the spin accumulation signal are mainly dominated by the variation of the interfacial spin polarization of the Co/Ag interface.