Effect of High Permeability Film in Magneto-optic Readout Head

A readout head combining a high-permeability film and a readout film was fabricated, and the effects of the high-permeability film were studied. Inclusion of the high-permeability film produces a steep increase in the variation of magnetic domain width with respect to the external magnetic field. The magnetic garnet film with the larger change in domain width without the high-permeability film had a similarly larger response with the film. When the magnetic domain width variation was greater than half the spot diameter, saturation occurred at a readout signal level of around 75dB.