Surface contribution to giant magnetoresistance in Fe/Cr/Fe films

Transport properties of very thin films have been analysed using the layered potentials calculated by means of the ab initio method represented by the density functional theory (DFT) in the planar geometry for the nFe/3Cr/nFe films, where n is the number of monoatomic Fe layers, (1 ≤ n ≤ 8). We also take into consideration the values of the relaxation time and the effective mass of an electron in terms of the considered potentials. The matching conditions have been applied at the interface and the boundary conditions at the surface in order to determine the contributions to the giant magnetoresistance (GMR) coming from the surface, interface, and inner layers. The surface roughness is introduced by means of the specularity factor Pσ defined in the spin-dependent terms responsible for the scattering of the electrons. Thus, the electron scattering at the outer surfaces depends on both spin orientations. The main result obtained in the paper is the evaluation that the surface contribution to GMR is very small in comparison with the effect of interface.