Today’s computers work by moving and storing electronic charge. But manipulating another property of electrons, their quantum-mechanical “spin,” would be faster and take far less energy. Researchers have been working on “spintronics” for years, and now electrical engineers at the University of Delaware and at Cambridge NanoTech in Cambridge, MA, have made the first prototype device that measures spin in silicon.
Electron spins come in two directions, up and down, which could represent the 1 and 0 of binary computation if spin could be controlled and detected. In the prototype, energized electrons first hit a magnetic cobalt-iron layer, which filters out electrons with down spin. The remaining up electrons pass through a 10-micrometer silicon layer and hit a detector consisting of a nickel-iron layer on top of a copper layer; all the layers sit on a silicon substrate. “It’s a very ingenious scheme to electrically generate and transport spins in silicon, [to] electrically detect the spins, and doing all of this on a chip,” says David Awschalom, a physicist who studies semiconductor spintronics at the University of California, Santa Barbara.