A correlation was found between magnetic viscosity in thin films, which was the origin of thermal loss effects, and the concentration of local face-centered cubic-like regions. The concentration of these defects, and the type and density of stacking faults, was varied by growing samples on various underlayers (Cr, CrTa/Cr) and was measured using grazing incidence X-ray scattering involving synchrotron radiation. It was shown that a substantial percentage of local face-centered cubic regions, in an otherwise hexagonal close-packed Co-alloy film, led to significant magnetic viscosity effects in modest magnetic fields. It was found that the activation volume was reduced for a sample having a higher percentage of face-centered cubic regions, and it was suggested that this could be explained in terms of the effect of weak links which acted so as to stabilize local micromagnetic configurations.

Effects of Stacking Faults on Magnetic Viscosity in Thin-Film Magnetic Recording Media. P.Dova, H.Laidler, K.O'Grady, M.F.Toney, M.F.Doemer: Journal of Applied Physics, 1999, 85[5], 2775-81