Comparative Analysis of Structural and Magnetic Properties in Co/Cu and Co/W Multilayers

Abstract

Gilbert damping in symmetric Cu/Co/Cu and asymmetric Cu/Co/W multilayers was studied as a function of Co thickness using FMR linewidth measurements. W-capped multilayers showed higher intrinsic damping across all thicknesses, due to strong SOC in W, which enhances spin-pumping, and MDL formation at the Co/W interface, increasing spin-flip scattering. The higher spin-mixing conductance in W-capped multilayers is linked to stronger SOC and enhanced orbital hybridization at the Co/W interface. X-ray diffraction revealed an fcc(111) phase in Co layers up to 4 nm thick, with thicker films showing a mix of fcc(111) and hcp(0001) textures. The Co thin films showed saturation magnetizations near literature values. No dead layer was found in Cu-capped multilayers, however, a 0.3 nm MDL formed in W-capped multilayers due to atomic intermixing at the Co/W interface. FM/NM interfaces are crucial in generating and dissipating pure spin currents, and they significantly impact the damping properties through the influence of seed and capping layers.