Control of wall coercivity and its effect on dynamic characteristics in magneto-optic materials

By observing thermomagnetically recorded domains of amorphous TbFeCo(Cr) thin films inside a polarized microscope, wall coercivities were estimated from the field which was needed to move the domain walls. The values were identical to those of the initial magnetizing field of as-deposited films having maze domain patterns. The distinct dependence of the wall coercivities on sputtering conditions observed, such as Ar gas pressure during the sputtering process and especially the Ar ion etching of silicon nitride underlayer prior to the magnetooptic layer deposition. In a dynamic recording experiment, carrier level subsequently revealed a sharp response versus externally applied magnetic field for materials with low wall coercivity, but indicated tradeoffs with relevance to read-out stability of the recorded domains. Particular attention was given to the effect of etching treatment upon the recording characteristics