Low probability of bulk spin-flip in mesoscopic Cu wires

Spin-flip probabilities from bulk defects and phonons are determined for the mesoscopic Cu channels of nonlocal spin valves (NLSVs). The NLSV spin signals are analyzed by a new approach to consistently extract the in situ values of the Cu spin diffusion length, effective spin injection (detection) polarization, and Cu resistivity. The size variations of the spin injectors (detectors) between NLSVs are treated by normalizing the spin signals to be commensurate with a standard injector (detector) size. The microstructure variations are statistically accounted for by measuring many NLSVs on the same substrate. From the Cu resistivity and spin diffusion lengths at 10 K and 295 K, the spin-flip probabilities from bulk defects and phonons are determined to be (3.9 +/- 0.8) x 10(-4) and (2.8 +/- 1.2) x 10(-4), respectively.