  There has been recent controversy about the magnitude of spin-flipping in the
heavy metal Pt, characterized by the spin-diffusion length, lsf(Pt) We propose
a resolution of this controversy, and also present evidence for the importance
of a phenomenon neglected in prior studies of transport across sputtered
Ferromagnetic/Pt (F/Pt) interfaces, spin-flipping at the interface. The latter
is characterized by an interface spin-flipping parameter, delta(Co/Pt) that
specifies the probability P = [1 - exp(-delta)] of a conduction electron
flipping its spin direction as it traverses a Co/Pt interface. From studies of
the Current-Perpendicular-to-Plane (CPP) Resistances and Magnetoresistances of
sputtered ferromagnetically coupled Co/Pt multilayers by themselves, and
embedded within Py-based Double Exchange-biased Spin-Valves, we derive values
at 4.2K of delta(Co/Pt) = 0.9 (+0.5/-0.2), the interface specific resistance,
AR*(Co/Pt) = 0.74 +/- 0.15 fohm-m(2). and the interface spin-scattering
asymmetry, gamma(Co/Pt) = 0.58 +/- 0.12. This value of delta(Co/Pt) is much
larger than ones previously found for interfaces involving Co but not Pt. To
derive delta requires knowledge of the spin-diffusion length, lsf(Pt), for our
sputtered Pt. We derive lsf(Pt) from separate measurements. Combining our
results with those from others, we find that lsf(Pt) for Pt is approximately
proportional to the inverse resistivity, 1/rho(Pt).
