Large Electron Spin Polarization, Basis for Future Computers, Proven in SiliconThe first effective spin injection method for silicon |
By Lucian Dorneanu, Science Editor
17th of July 2007, 12:17 GMT
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All currently used electronic devices rely on electron charge to function and to transmit information. A new science, called spintronics, tries to switch to using their spin instead of charge, thus potentially continuing the miniaturization process that is rapidly approaching its physical limits with current technologies.
Spintronics is an emerging field that could be used to
create incredibly efficient electron spin-based photonic devices, which in turn may be used to build, for example, computers with extraordinary capacities.
Practical applications such as circuits based on spintronics are promising, but for now, this promise has not been fulfilled using conventional semiconductor materials, like silicon, as researchers are still trying to overcome some major problems, like the fact that single electrons can't be pinned down and their spin-orientation is not permanent.
The latest advancement in this field is the demonstration of the first efficient electrical spin injection into silicon, the semiconductor that governs all of our electronic industry. A group of researchers at the Naval Research Laboratory (NRL) have efficiently injected a current of spin-polarized electrons from a ferromagnetic metal contact into silicon.
This injection produced a large electron spin polarization in the semiconductor, meaning that this fundamental property of the electron, the spin angular momentum, could be used to store, retrieve and process information future applications.
For now, this method seems to work with silicon, in which spin polarization has been previously extremely hard to achieve and control. Producing efficient spin injection and transport in silicon is regarded as the "holy grail" of semiconductor spintronics and the news seems to be heading in the right direction.
It's the second time scientists were able to inject a current from a ferromagnetic metal, like an iron film, into silicon, to produce the long sought high electron spin polarization, an effect that should greatly facilitate the development of silicon-based spintronic devices.
Ian Appelbaum and Biqin Huang of the University of Delaware in Newark, US and Douwe Monsma of Cambridge NanoTech, Massachusetts, US, successfully demonstrated the first electrical injection of spin into silicon, in May, this year.
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