Origin of spin-polarization decay in point-contact Andreev reflection

We have performed point contact Andreev reflection measurements with a view to study the correlation between measured spin polarization and the interface scattering parameter Z extracted from fits of the modified Blonder-Tinkham-Klapwijk model to the conductance-voltage curves of superconductor/ferromagnet point contacts. A simple model describing spin-flip scattering in the interface region identifies (formula presented) as the effective scattering parameter and predicts that the spin polarization decays exponentially with (formula presented) in agreement with experimental data.