Magnetooptical Recording with Optical Modulation and Magnetic Field Modulation

The magnetooptic recording characteristics of three types of DyFeCo films with a quadrilayer structure were measured using three recording methods: optical modulation, magnetic field modulation and the laser-off method. In the laser-off method, the laser power was lowered only while the magnetic field was changing. The transition metal (TM)-rich medium had the best carrier-to-noise (C/N) ratio when using the optical modulation method. When using magnetic field modulation, the C/N was lower than for optical modulation recording. The three media had similar characteristics when using magnetic field modulation. Adoption of the laser-off method improved the C/N and the magnetic field dependence of the C/N. In particular, the TM-rich medium exhibited the same C/N as when using optical modulation.