  We measure the spin-charge interconversion by the spin Hall effect in
ferromagnetic/Pt nanodevices. The extracted effective spin Hall angles (SHAs)
of Pt evolve drastically with the ferromagnetic (FM) materials (CoFe, Co, and
NiFe), when assuming transparent interfaces and a bulk origin of the spin
injection/detection by the FM elements. By carefully measuring the interface
resistance, we show that it is quite large and cannot be neglected. We then
evidence that the spin injection/detection at the FM/Pt interfaces are
dominated by the spin polarization of the interfaces. We show that interfacial
asymmetric spin scattering becomes the driving mechanism of the spin injection
in our samples.
