Bilayer graphene is another step towards graphene electronics
12 August 2011
The Nobel Prize winning scientists Professor Andre Geim and Professor Kostya Novoselov have taken yet another step forward in studying the new ‘wonder material’ graphene and revealing its exciting electronic properties that can be put to use in future electronic applications.
The academics that discovered the world’s thinnest material at The University of Manchester in 2004 have revealed more about the electronic properties of its slightly fatter cousin; bilayer graphene.
The researchers, from the universities of Manchester (UK), Nijmegen (the Netherlands) and Moscow (Russia), have studied in detail the effect of interactions between electrons on the electronic properties of bilayer graphene.
They used extremely high-quality bilayer graphene devices that are prepared by suspending sheets of the material in vacuum. This way, most of the unwanted scattering mechanisms for electrons in graphene could be eliminated; enhancing the effect of electron-electron interaction.
The latter could be seen as strong changes in the low-energy electronic spectrum – it becomes strongly anisotropic, or directionally dependent. This is the first effect of its kind where the interactions between electrons in graphene can be clearly seen.
The reason for these unique electronic properties is that quasiparticles (electrons and holes, that carry electric current) in this material are very different from those in any other metals. They possess chiral symmetry (a symmetry between electrons and holes) of the sort which exist between particles and antiparticles in high-energy physics.
Due to such properties, graphene-based materials are sometimes called ‘CERN on a desk’ – referencing the Large Hadron Collider in Switzerland. This is just one of the reasons why the electronic properties are particularly exciting and often bring surprises.
Graphene is a novel two-dimensional material which can be seen as a monolayer of carbon atoms arranged in a hexagonal lattice. When two layers of graphene are bonded in a certain manner, they form bilayer graphene; an interesting and unusual material in its own right. Both graphene and bilayer graphene possesses a number of properties, such as extremely high electron and thermal conductivities due to very high velocities of electrons and high quality of the crystals, as well as mechanical strength.
Professor Novoselov said: “The technology of graphene production matures day-by-day, which has an immediate impact both on the type of exciting physics which we find in this material, and on the feasibility and the range of possible applications.”
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