Newly-developed 'graphone' makes spintronic devices closer than ever
September 3, 2009
A team of researchers from the Virginia Commonwealth University, Peking University in Beijing, the Chinese Academy of Science, and Tohoku University in Japan has designed a new graphite-based magnetic nanomaterial that behaves as a semiconductor and could prove very important for ongoing research in the field of spintronics.
Spintronics, or magnetoelectronics, is an emerging technology that harnesses the spin of electrons along with their electrical charge to store and transfer information in digital form. Because the electronic spin is closely related to magnetism, techniques that attempt to manipulate these particles must present strong and highly controllable magnetic properties.
Graphene: a possible substitute for silicon?
First isolated by English and Russian researchers in 2004, graphene is a one-atom thick sheet of carbon atoms densely-packed in a honeycomb structure with unique mechanical and electronic characteristics.
Graphene has a breaking strength 200 times greater than steel, and has proven an excellent choice in manufacturing highly resistant carbon nanotubes, which have quickly become one of the central research areas in today's nanotechnology.
But graphene also shows excellent electrical properties that, like silicon, can be precisely controlled by adding trace concentrations of impurities. Such impurities form chemical bonds with the existing atomic structure and release electrically-charged particles — either negatively-charged electrons or positively-charged 'electronic holes' — that alter the conductivity of the material.
This makes graphene apt for a number of applications in electronics, and particularly in integrated circuitry where, because of this and a number of other unique characteristics, it has the potential to become an excellent substitute for silicon.
Graphone, a carbon sheet with a twist
As explained above, in order for spintronics to fully flourish, there needs to be a way to precisely manipulate the spin of electrons. Because magnetism and electronic spin are so closely related, using a magnetic material is perhaps the most natural way of addressing the issue.
An international team recently designed a material that adds magnetism to the properties of graphene while retaining its structural integrity and most of its electrical properties. The so-called 'graphone' is therefore a very strong candidate for future applications in spintronics.
"The new material we are predicting, graphone, makes graphene magnetic simply by controlling the amount of hydrogen coverage — basically, how much hydrogen is put on graphene. It avoids previous difficulties associated with the synthesis of magnetic graphene," distinguished professor Puru Jena, who was part of the team, explained.
This approach is in fact quite different from other graphene nanostructures such as one-dimensional nanoribbons and two-dimensional nanoholes, where zigzag edges are necessary for magnetism, as explained in a paper written by the group and published in the latest edition of the journal Nano Letters.
The research was founded by the National Natural Science Foundation of China, The National Science Foundation and by the U.S. Department of Energy.
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