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April 25, 2007

Graphene 'spintronic' devices

The Brookhaven group uses magnetism to manipulate spin in graphene, a material consisting of flat sheets of carbon atoms arranged in a hexagonal pattern. They've proposed ways to make materials consisting of layers of graphene mated to magnetic and nonmagnetic layers.

These "graphene-magnet multilayers" (GMMs) are expected to retain their properties at room temperature, an important practical requirement for spintronic devices. By properly arranging the magnetization of the magnetic layer(s), they can be used to create a full spectrum of spintronic devices, including (re-)writable microchips, transistors, logic gates, and more. Using magnetism for spin manipulation also opens exciting possibilities for creating active, re-writable and re-configurable devices whose function changes depending on the magnetization pattern written on the magnetic medium.

"Graphene is quite unique," Zaliznyak says, "in that an ideally balanced sheet is neither a conductor nor an insulator. Related to this is the fact that electrons in graphene behave in such a way that their mass effectively vanishes!" In other words, he explains, they move without inertia, like rays of light or particles accelerated to relativistic speeds — that is, close to the speed of light.

"This development can open the way for the use of spintronics in practical room temperature devices, an exciting prospect," said DOE Under Secretary for Science Raymond L. Orbach.

The graphene spintronic devices are competing with organic nanowires and some other materials for spintronics.

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