MAGNETORESISTIVE MEMORY TECHNOLOGY

Magnetoresistive random-access memory (MRAM) is an integrated combination of non-volatile thin film magnetic storage and semiconductor support circuits. MRAMs fill unique product niches and are useful today. The ultimate potential of MRAM is to be the "next dynamic random-access memory", but it can only be realized with higher signals, and the giant magnetoresistance (GMR) effect offers a direct solution. GMR has been noted in thin film multilayers having ferromagnetic films interleaved with conductor layers. Composite thin films have demonstrated magnetoresistance on the order of ten times the anisotropic magnetoresistance of the present magnetic materials. A brief literature review, a simple model and some data on the "spin valve" effect are presented. These materials can offer improvements of 100 in read time and substantial simplification in circuitry when applied to MRAM. Thin magnetic films demonstrating GMR and future MRAM memory cells using films a few monolayers thick with limited cell diameters (1000 angstrom) pose very interesting fundamental problems relating to ferromagnetism and transport theory, and also offer challenges in fabrication and measurement.