We report experimental study of spin transport in all-metal nanowire spinvalve structures. The nanowires have a diameter of 50 nm and consist of threelayers - cobalt, copper and nickel. Based on the experimental observations, weconclude that the primary spin relxation mechanism in the paramagnet copper isthe Elliott-Yafet mode associated with frequent interface roughness scattering.This mode is overwhelmingly dominant over all other modes, so that we are ableto study the pure Elliott-Yafet mode in isolation. We deduce that the effectivespin relaxation length associated with this mechanism is about 16 nm in ournanowires and is fairly independent of temperature in the range 1 - 100 K. Thecorresponding spin relaxation time is about 100 femtoseconds. We also find thatthe spin relaxation length or time is fairly independent of the electric fielddriving the current in the range 0.75 - 7.5 kV/cm.
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