First-principles study of ballistic transport properties in Co2MnSi/X/Co2MnSi(001) (X = Ag, Au, Al, V, Cr) trilayers

We investigate and discuss the origin of interface resistance in magnetic trilayers with the half-metallic Co2MnSi by performing first-principles electronic-structure and ballistic transport calculations for Co2MnSi/X/Co2MnSi(001) (X = Ag, Au, Al, V, Cr). We found that the matching of the Fermi surface projected to the two-dimensional Brillouin zone of in-plane wave vector (k(parallel to)) is a main contributing factor for the spacer (X) dependence of the interfacial resistance. Furthermore, the MnSi-terminated interface shows low resistance compared with the Co-terminated interface because the Co-terminated interface has a larger d component in the local density of states at the Fermi level than that of the MnSi-terminated interface. We conclude that Ag, Au, and Al spacers with MnSi termination of CMS/X/CMS trilayers will provide the large interfacial spin-asymmetry coefficient because of the small interface resistance in parallel magnetization.