Absence of high surface spin-flip rate in mesoscopic silver channels

Abstract

Large spin signals up to 38 mΩ are demonstrated in mesoscopic nonlocal spin valves with silver channels. Scanning electron microscope images reveal Volmer–Weber growth of the silver channels, which consist of coalesced silver islands from 30 to 80 nm in size. The temperature dependence of the spin signals is monotonic, in contrast to previously observed non-monotonic features due to high surface spin-flip rate. We hypothesize that magnetic impurities in the silver are primarily segregated at the bulk grain boundaries instead of near the side surfaces of the channel, resulting in an absence of high surface spin-flip rate.