First-principles study of ballistic transport properties in Co${}_{2}$MnSi/$X/$Co${}_{2}$MnSi(001) ($X=$ Ag, Au, Al, V, Cr) trilayers

First-principles study of ballistic transport properties in Co $_{2}$ MnSi/ $X /$ Co $_{2}$ MnSi(001) ( $X =$ Ag, Au, Al, V, Cr) trilayers

Yoshio Miura, Koichi Futatsukawa, Shohei Nakajima, Kazutaka Abe, and Masafumi Shirai

Phys. Rev. B 84, 134432 – Published 20 October 2011

Abstract

We investigate and discuss the origin of interface resistance in magnetic trilayers with the half-metallic Co $_{2}$ MnSi by performing first-principles electronic-structure and ballistic transport calculations for Co $_{2}$ MnSi/ $X /$ Co $_{2}$ MnSi(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 ( $k_{∥}$ ) 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.