Element-specific characterization of the interface magnetism in[Co2MnGe∕Au]nmultilayers by x-ray resonant magnetic scattering

Abstract

The magnetism of the ferromagnetic half-metallic Heusler compounds at the interface with other metals, insulators, and semiconductors is a critical issue when judging the prospects for these materials to be used in future spintronic devices. We study the interface magnetism of the ferromagnetic half metal ${\mathrm{Co}}_{2}\mathrm{Mn}\mathrm{Ge}$ in a high-quality ${[{\mathrm{Co}}_{2}\mathrm{Mn}\mathrm{Ge}∕\mathrm{Au}]}_{50}$ multilayer by x-ray resonant magnetic reflectivity using circularly polarized x-ray radiation in the energy range of the Co and Mn ${L}_{2,3}$ edges. An analysis of the magnetic part of the reflectivity at the superlattice Bragg peaks allows a precise determination of the magnetization profile within the ${\mathrm{Co}}_{2}\mathrm{Mn}\mathrm{Ge}$ layers. We find that the profile is definitely different for Mn and Co spins and asymmetric with respect to the growth direction. At room temperature nonferromagnetic interface layers exist with a thickness of about 0.45 nm at the bottom and 0.3 nm at the top of the ${\mathrm{Co}}_{2}\mathrm{Mn}\mathrm{Ge}$ layers. Additionally, the comparison of the nonresonant and resonant magnetic diffuse scattering reveals that the correlated structural and magnetic roughness are almost identical, the corresponding length scale being the in-plane crystallite size.