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 theproblem 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.
quote: The team from Delaware and Massachusetts appears to have overcome the problem by keeping the layers of silicon and ferromagnetic materials extremely thin -- only 10 microns and 5 nanometers, respectively -- and by using high-energy electrons .