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Illustration of the breakthrough method of electron spin injection, precession, and detection in silicon. (Source: University of Delaware, Ian Appelbaum)
A breakthrough in this promising field of nanoelectronics could revolutionize the design of digital devices

A new generation of electronics that are vastly smaller, faster, and more power-efficient came closer to fruition this month thanks to the work of a team of U.S. scientists.

As described in this month's academic journal Nature (subscription required), researchers Ian Appelbaum and Biqin Huang of the University of Delaware and Douwe Monsma of Massachusetts-based Cambridge NanoTech have succeeded in creating a working spintronic device based on conventional silicon.

Spintronics is a promising approach to creating electronic devices that store information based on the spin of electrons, rather than the more cumbersome conventional method of relying on the electron's charge.

An electron's spin refers to its directional rotation. Unlike a spinning tire or a toy top, an electron's spin is a quantum property, and thus a constant value that does not change. Scientists are working to harness this property by aligning multiple electrons so they all spin in the same direction. This polarization allows the creation of a spin current as well as a current of electrical charges.

One of the major drawbacks to creating practical spintronic devices has been the inability to use silicon substrates. Aligning the spin of electrons requires the use of ferromagnets. However, ferromagnets bonded to silicon have a scrambling effect on the electrons, making the creation of a coherent stream of polarized electrons difficult to achieve.

The team from Delaware and Massachusetts appears to have overcome the
problem by keeping the layer ferromagnetic material extremely thin -- only 5 nanometers -- and by using high-energy electrons. The team was also able to reverse the spin of the electrons by applying a magnetic field.

The ability to create spintronic devices using conventional silicon substrates rather than metal or gallium arsenide makes the approach significantly more viable, since it could theoretically be adapted to the existing silicon-based manufacturing processes that are prevalent in the electronics industry.

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Error checking needed to ensure data integrity.
By Goty on 5/18/2007 12:36:34 PM , Rating: 2
There would have to be some kind of error checking involved in this technology to ensure the integrity of the data being stored, because electron spins are not constant.

An electron can spontaneously "flip" its spin from spin up to spin down (or vice versa), which could cause a definite problem with data storage.

The average timescale for this to happen in a single electron is somewhere around 11 million years, but when you consider the fact that there are about 10^24 electrons in unfilled energy levels in a single mole of silicon (only about 28g), there's a decent chance that this could happen and that it could corrupt your data.

By Rotkiv on 5/18/2007 12:57:32 PM , Rating: 2
They better ensure that they get "new" electrons in that case. ;)

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