New memories tap spin, gird for battle.

After decades of running on half its cylinders, the electronics revolution will soon double its horsepower, say scientists from two electronics giants. Almost all the spectacular advances in microprocessors and computer memories to date have exploited only the charge of the electron. The electron's inherent magnetism, or spin, however, can also encode data.

Honeywell and IBM both announced on March 25 that they have built prototype spin-memory chips with speeds comparable to today's charge-based chips. Because these spin memories retain data when shut off, computers based on them will start instantly, without having to load data from disks.

Theodore Zhu of Honeywell in Plymouth, Minn., says that the company expects to offer a 1-megabit spin-based memory chip commercially this year. It will make use of a property known as giant magnetoresistance (GMR). In a conductor with GMR, applied magnetic fields markedly change electrical resistance (SN: 4/22/95, p. 245).

Work on a rival spin-memory design incorporating so-called magnetic tunneling junctions was described by Stuart S.P. Parkin of IBM in San Jose, Calif. The junctions operate more quickly than GMR circuits and can pack bits more densely, he says. GMR, however, which is already used widely in disk-drive heads, is the more mature technology. Parkin predicts that IBM will bring tunneling-junction memories to market in 3 to 5 years.