ABSTRACT
Until recently, purely two-dimensional (2D) materials were thought perhaps not to exist in nature. Physicists who wanted to study transport or any other physical manifestation of quantum mechanics in two dimensions had no other choice but to fabricate 2D systems arti„cially by con„ning 3D ones in a plane (such that the energy spectrum in the con„ned dimension is effectively reduced to a single quantum level). Two-dimensional electron gases (2DEGs) were thus obtained by forming 2D quantum wells at the interface of semiconducting heterostructures such as GaAs-AlGaAs using elaborate electrostatic con„nement techniques. Since their discovery, these systems have been the source of meticulous studies and shown to exhibit novel quantum phenomena stemming from the in¥uence of con„nement on quantum particles: the quantum Hall effect, Coulomb blockade, and conductance quantization in ballistic quantum point contacts, to name but a few (Beenakker and van Houten 1991). However, these systems suffer from the experimental challenges that have to be met to ef„ciently control them since they are buried deep in the aforementioned heterostructures. The synthesis of graphene, a truly 2D crystal both stable and controllable at room temperature, was nothing shy of a revolution in this respect. What is this amazing material?
