DESIGN OF MAGNETOOPTIC PHASE-OPTIMIZED TRILAYER SYSTEMS FOR THE ENHANCEMENT OF THE POLAR KERR-EFFECT

The methodology of designing magneto-optic phase-optimised tri-layer systems is described. These systems enhance the polar Kerr effect and maximise the signal-to-noise ratio associated with the differential readout of stored information in magneto-optic recording technology. The improvements are achieved by obtaining the most appropriate values for the disc reflectance and ensuring that the associated Kerr rotation is as large as possible whilst, at the same time, maintaining zero Kerr ellipticity. Thus, the absolute maximum performance is achieved for any given material and the need for phase-correcting optics in the readout head is removed. Designs are presented based on Co/Pt superlattices and TbFeCo amorphous films. In the case of Co/Pt, examples are given for the spectral range 380-850 nm. Indications are that, after enhancement, the performance over this range of wavelengths does not vary significant.