Magnetic and structural studies in sputtered Co/C multilayers

Co/C multilayers have been prepared by triode sputtering under controlled conditions. Their structural, magnetic, and FMR (ferromagnetic resonance) properties have been investigated. For t (Co)<4 nm, an amorphous-like structure which upon annealing goes to the hexagonal Co₂C phase is formed. Hexagonal structure is obtained for t(Co)>6 nm. The magnetization decreases steeply for t(Co)<6 nm. In-plane uniaxial anisotropy is induced in the multilayers and depends on t(C). H_c decreases with t(Co). In-plane uniaxial anisotropy is induced by layering. FMR studies show that perpendicular anisotropy is present for t(Co)>8 nm, and an easy plane is present for t(Co)<8 nm