A high-density magneto-optic memory

A magneto-optic memory element which was first proposed by Chang et al. has been investigated. The element is based upon the properties of ferrimagnetic materials with a compensation temperature. It is a single crystal wafer of gadolinium iron garnet. The importance of domain walls in limiting the minimum size of a bit was recognized. This limitation was removed by scribing the wafer into square bits approximately 25 microns on a side. The reading operation was improved by utilizing a beam splitting procedure similar to one suggested by Miyata and Lentz. The optimum thickness of the memory element and the optimum wavelength for memory operation were determined. Thermal considerations were investigated. The laser power required for the writing operation and limits for the writing speed set by thermal factors were determined. Experimental results were in good agreement with these theoretical predictions.