Activation volumes of reversal in Tb-Fe-Co thin films

The first generation of magneto-optic (M-O) data storage systems use rare earth - transition metal (RE-TM) alloys as the storage media. The materials typically used are Tb - Fe/Co thin film alloys protected by passivating dielectric layers on either side of the M-O layer. In this paper we present measurements of the activation volumes of reversal in such materials, obtained from magnetic time dependence measurements. Activation volumes are of interest as they set the fundamental limits to the maximum storage density obtainable from any media, being the volume of material that nucleates the generation of a reversed domain. The wavelength of laser light available and the quality of optical systems currently set the technological limits of storage density.