Correlation of switching volume with magnetic properties, microstructure, and media noise in CoCr(Pt)Ta thin films

The technique of ''field sweep-rate dependence of coercivity'' together with the delta-M curves, transmission electron microscopy, and media noise measurement have been employed to reveal the correlation among the magnetic switching volume, physical grain size, intergrain interaction, and noise properties. The switching volume for both CoCrTa and CoCrPtTa films was found to be similar to 15 nm in diameter, and weakly dependent on grain size and coercivity for the systems studied. In films with physical grain size larger than the switching volume, strong intergrain interaction and high media noise is observed. In films with the physical grain size close to the switching volume, smaller interactions and lower media noise is found. It is argued that a change of the grain size results in a change in the nature of the magnetic interactions. (C) 1997 American Institute of Physics.