Researchers have taken the first step toward building silicon-based computers that use a fraction of the power of today's machines. A team has injected electrons into silicon in such a way that their spins, or magnetic orientations, tend to be aligned in one direction instead of the other.
In the new device, Appelbaum and co-workers inject electrons from a layer of aluminum through a thin layer of ferromagnet (a permanent magnet) and into a pure silicon crystal. Aluminum has a 50–50 mix of spin up and spin down electrons - the two possible orientations. The ferromagnet, however, blocks electrons of one spin while letting the others flow into the silicon.
The researchers found that their ferromagnet barrier gave silicon a one percent excess of one spin type versus the other, at a temperature of 85 kelvins, they report in a paper published online today in the journal Nature.