  We utilize nanoscale spin valves with Pt spacer layers to characterize spin
scattering in Pt. Analysis of the spin lifetime determined from our
measurements indicates that the extrinsic Elliot-Yafet spin scattering is
dominant at room temperature, while the intrinsic Dyakonov-Perel mechanism
dominates at cryogenic temperatures. The significance of the latter is
supported by the suppression of spin relaxation in Pt layers interfaced with a
ferromagnet, likely caused by the competition between the effective exchange
and spin-orbit fields.
