The role of interfaces in the magnetoresistance of Au/Fe/Au/Fe/GaAs(001)

The electron transport and magnetoresistance (MR) were investigated in high quality crystalline epitaxial Fe(001) and Au(001) films and exchange coupl ed Au/Fe/Au/Fe/GaAs(001) trilayer structures. Fits to the experimental data were based on the semiclassical Boltzmann equation, which incorporates the electronic properties obtained from first-principles local density functio nal calculations. The fits require a surprisingly high asymmetry for the sp in dependent electron lifetimes in Fe, tau (down arrow)/tau (up arrow) = 10 at room temperature. Despite the large atomic terraces at the Au/vacuum an d Fe/GaAs interfaces the scattering at the outer interfaces was found to be diffuse. The origin of MR in Au/Fe/Au/Fe/GaAs(001) structures is due to el ectron channeling in the Au spacer layer. The measured MR is consistent wit h the diffusivity parameters s(up arrow) = 0.55, s(down arrow) = 0.77 at th e metal-metal interfaces. (C) 2001 American Institute of Physics.