Structural, magnetotransport, and optical properties of sputtered Co/Cu multilayers examined as a function of Co layer thickness at the second antiferromagnetic maximum

Abstract

A series of {[Co(tCo)/Cu(2.1 nm)]30/Co(tCo)}30 multilayers have been deposited under specific magnetron sputtering deposition conditions that lead to giant magnetoresistance (GMR) curves with technological interest. X-ray reflectivity, magnetic, magneto-transport, and spectroscopic ellipsometry measurements were used together to examine the dependence of their properties upon the Co layer thickness (tCo). Remarkably, the obtained film density and roughness, the saturation and coercivity fields, the reduced remnant magnetization, the GMR ratios, and the plasma frequency exhibit a significant divergence as a function of tCo in the range between 1.3–1.6 nm. The observed microstructural, magneto-transport, and magnetic relative differences, induced in (111) textured Co/Cu multilayers by varying the tCo, were correlated with changes of the optical electronic states of the constituents in the electronic density of states near the Fermi level.