When one writes with a pencil, thin crystallites of graphite are left on the surface. Some of them are only one atom thick and can be viewed as individual atomic planes pulled out from bulk graphite or as a chicken wire made from carbon bonds. Until three years ago, this strictly 2D material called graphene was presumed not to exist in the free state. Now graphene is a rapidly rising star on the horizon of materials science and condensed matter physics, revealing a cornucopia of new physics and potential applications.
Whereas one can be certain of the realness of applications only when commercial products appear, graphene no longer requires any further proof of its importance in terms of fundamental physics. Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of “relativistic” condensed matter physics, where quantum relativistic phenomena, some of which are unobservable in high energy physics, can now be mimicked and tested in table-top experiments. More generally, graphene represents a conceptually new class of materials that are only one atom thick and, on this basis, offers new inroads into low-dimensional physics that has never ceased to surprise and continues to provide a fertile ground for applications.
I will overview our experimental work concentrating on electronic properties of graphene, which are governed by Dirac-like equations rather than the standard Schrödinger equation. Most unusual phenomena found in graphene include two new types of the quantum Hall effect, a finite conductivity e2/h in the limit of vanishing carrier concentrations, the suppression of weak localization and an intrinsic microscopic crumpling of free-hanging graphene.
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