Magnetic domain observations in 50-percent Ni-Fe tapes

Domain observations using the Kerr effect have been made on 50-percent Ni-Fe grain oriented tapes of 50-μm (2-mil) and 100-μm (4-mil) thickness. The surface domain patterns differ depending on sample preparation, which is described in detail. When the tape samples were annealed and then electrochemically polished, complex patterns, suggestive of surface stresses, appeared. When the tape samples were annealed after electrochemical polishing, the patterns observed were in close agreement with previously postulated models for flux reversal in 50-percent Ni-Fe tapes. Correlations of surface domain structure with net magnetization were also made by inductive pickup, and data on the observed coercive forces are included.