New spin on transistor heralds chip revolution

A fundamental breakthrough in solid-state physics has been announced this week by Swedish researchers. By adding manganese to an existing semiconducting material, zinc oxide, Professors Venkat Rao and Borje Johansson at the Royal Institute of Technology in Stockholm say that they have added magnetic properties without destroying its previous capabilities.

Although this has been done before with other materials, most notably gallium arsenide, this is the first time a substance has been produced that will work at room temperature. Circuits made with the new material have the potential to run hundreds of times faster or store thousands of times more information than current electronic designs, the researchers say.

Professor Rao told ZDNet UK that "Zinc oxide is already widely used in optoelectronics and mobile phones, so it should be only two to three years before new devices are produced." Smaller, faster versions of zinc oxide's existing repertoire of optical modulators, detectors, lasers and so on should be easy to produce. The biggest win, however, will be in the use of the compound for spintronic transistors, quantum devices that until now have been limited to laboratory demonstrations.

Spintronic transistors have the potential to be much faster and dissipate much less power than conventional designs because they set and test the spins of electrons -- the fundamental component of magnetism -- without needing an electric current.

"You can get much closer to the speed of light," said Rao, "because you're not moving charge around." The logic state of a spintronic device is also non-volatile, and stays when power is removed. "It's like having a hard disk without the magnetic surface," Rao said, "and you can have very high density at low power." He said that because semiconductor engineering is so highly advanced, it should only be five to ten years before spintronic devices appeared: "But don't ask me exactly when. That would be like asking a newly-wed woman when the first baby was expected."

Spintronics is under intensive investigation at many other establishments, because of its potential for thousand-fold increases in memory storage, power saving and device speed. IBM is investigating MRAM -- magnetic memory -- based on the technology, and Stanford University recently announced the discovery of an 'Ohm's Law' for spin. That predicts that room temperature devices could effectively manipulate electron spin with little or no power loss at all. "In maybe a ten year timeframe, spintronics will be on a par with electronics," Professor Shoucheng Zhan of Stanford said in a statement.