Effect of interfacial s-d scattering on transport in structures ferromagnet/insulator/ferromagnet

A two-band s-d model based on the Green function method has been developed for calculating the conductivity and tunnel magnetoresistance of ferromagnet/insulator/ferromagnet structures. It is shown that s-d scattering at the interface between the ferromagnet and the insulator in Fe/Al₂O₃/Fe increases the tunnel magnetoresistance. The spin polarization of the current decreases thereby and even becomes negative, which is mainly due to scattering of strongly localized d electrons to the s band, followed by tunnelling through the insulator.