CONTROL OF WALL COERCIVITY AND ITS EFFECT ON DYNAMIC CHARACTERISTICS IN MAGNETOOPTIC MATERIALS

By observing thermomagnetically recorded domains of amorphous TbFeCo(Cr) amorphous 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 initial magnetizing field of as-deposited films having maze domain-patterns. Distinct dependence of the wall coercivities on sputtering conditions were observed, such as Ar gas pressure during the sputtering process, and especially Ar ion etching of silicon nitride (SiN(x)) underlayer prior to the magneto-optic layer deposition. In dynamic recording experiment, carrier level subsequently revealed sharp response versus externally applied magnetic field for materials with low wall coercivity, but indicated trade-off with relevance to read-out stability of the recorded domains. Particularly the effect of etching treatment upon the recording characteristics were focused on in this paper, and studies were carried out to interpret the results in terms of investigating the relation between wall energy and the effective force of pinning site.