A direct-overwrite system for magneto-optical storage systems with circularly magnetized control layer

The principles of a new direct-overwrite system for magnetooptical memory systems are investigated. In this system, the conductive layer of the heatsink is magnetic with an in-plane easy axis parallel to the data tracks. Magnetic charge windows are created in the latter layer along the data tracks on the flanks of the temperature profiles produced by the focused laser energy. By varying the laser power, the charge and the associated field windows are modified and displaced with respect to the storage layer. Thus, the total field is reversed at the critical rim in the storage layer at which M is adjustable. Write fields larger than 40 kA/m and data rates on the order of 10 to 20 Mb/s can be realized. The performance of the system is studied by means of three-dimensional finite-element calculations of the temperature distribution in the moving film stack and three-dimensional field calculations. Appropriate control layers have been produced, and their stability has been experimentally investigated