Materials for Magnetoresistive Random Access Memory

MRAM technology is based on the storage of data in stable magnetic states using devices that have a large magnetoresistance effect, so that the data can be read by determining the resistance of the device. MRAM is inherently nonvolatile and the magnetic states can be switched extremely fast and with no wear out. In this article, we review the fundamentals of MRAM technology, explain the innovations that have overcome barriers to commercialization, and describe areas where further innovation can advance the technology most significantly. The influence of key structural and magnetic properties of materials used in magnetic tunnel junctions, and optimization of those devices for read and write performance in memory arrays, is discussed in detail. The various approaches to writing data in MRAM arrays are described and compared, with emphasis on toggle MRAM, the type that is in commercial production, and on spin-torque MRAM, which shows great promise for future improvements in power and density. In the final section, we summarize recent demonstrations of advanced MRAM technology.