We report experimental study of spin transport in all metal nanowire spin valve structures. The nanowires have a diameter of 50 nm and consist of three layers—cobalt, copper, and nickel. Based on the experimental observations, we determine that the primary spin relaxation mechanism in the paramagnet layer—copper—is the Elliott-Yafet mode associated with elastic scattering caused by charged states on the surface of the nanowires. This mode is overwhelmingly dominant over all other modes, so that we are able to study the pure Elliott-Yafet mechanism in isolation. We deduce that the spin diffusion length associated with this mechanism is about 16 nm in our nanowires and is fairly temperature independent in the range 1–100 K, which is consistent with the spin relaxation being associated with elastic scattering by surface states. The corresponding spin relaxation time is about 100 femtoseconds. We also find that the spin relaxation rate is fairly independent of the electric field driving the current in the field range 0.3–3 kV/cm.
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