James Hone: The World's Strongest Material, Measuring the Mechanical Properties of Graphene

Описание: Graphene is a most peculiar and unique material which consists simply of one atomic layer of carbon atoms arranged in a honeycomb lattice. As such graphene is the ultimate two-dimensional crystal since it is only one atom thick in the third dimension! It is, by definition, the thinnest material one can have. Amazingly, it is also the strongest and the stiffest material, and in some sense the fastest since electrons can move through graphene at very high speed even at room temperatures—the electron speed in graphene is thousands of times faster than that through the fastest silicon-based computer chips available in the market. These unique properties of graphene have attracted a great deal of attention from physicists, chemists, engineers, and materials scientists over the last five years, making graphene the most active research area in all of science during the recent years (as measured by the number of publications in the literature focusing on graphene). It is therefore quite remarkable that very little work focused on graphene until 2004 when Andre Geim and Kostya Novoselov (and their collaborators) demonstrated how easy it is to make graphene in the laboratory just by using scotch tape and pencils!

The great technological possibilities of graphene are actually just one aspect of its interesting properties. It turns out that graphene is a very strange quantum mechanical system where the electrons, as they are tunneling between the carbon atoms on the honeycomb lattice, obey not the standard Schrodinger equation (as most solid state materials do), but the chiral massless Dirac equation with the energy dispersion of the electrons being linear rather than quadratic as in most materials. Graphene can thus be thought of as a zero-gap semiconductor with both the electrons and the holes having kinetic energy linear (rather than quadratic) in momentum—the linear electron and hole bands cross each other at a point in momentum space which is called the Dirac point. This massless Dirac nature of graphene electrons lead to many truly strange properties which are absolutely fascinating in their own right as important as future technological applications of graphene.

The graphene Teachers’ Conference at KITP will immediately follow the week-long scientific conference on graphene also at KITP. Sankar Das Sarma of the University of Maryland, a theoretical physicist working on graphene, is coordinating the Teachers’ Conference.

Geared toward secondary school physics teachers in the U.S. KITP is eager to include teachers from population groups under-represented in physics.

January 14, 2012

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