Magneto-Optical Writing System with the Pulse Magnetic Field

A pulse magnetic field was used successfully in magneto-optical writing of bits of size smaller than the diameter of the spot of light. Applying a pulse magnetic field to the medium, when the sum of the signal field and the diamagnetic field becomes larger than the coercive force, the magnetization in that area is inverted. Raising the pulse frequency caused the polarity to overlap with reverse magnetic domains, canceling to form a "crescent" smaller than the light spot. In experiments, a lens focused semiconductor laser light to 5.6 ¿m, and signal and bias fields of 30 and 300 Oe were used to write bits 0.45 ¿m in width and 2 ¿m in length.