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Friday, August 31, 2012
Physics Building, Room 204
Note special time.
[Host: Genya Kolomeisky]
College of William & Mary
"Graphene: how electrons move and interact in the ultimate flatland"
Graphene is a one atom-thick layer of carbon atoms arranged in a two-dimensional honeycomb lattice that was first realized in a laboratory in 2004. In graphene the electrons are strictly confined to live in two dimensions and behave as massless Dirac fermions described by two-dimensional Quantum Electro Dynamics (QED), albeit with a much lower (1/300 th) speed of
light and bigger (≈ 1), and tunable, fine structure constant. Due to its
unique electronic structure graphene exhibits anomalous electronic properties. In this talk I will discuss the unusual transport properties of graphene and provide a theoretical explanation of the "puzzles" posed by graphene
transport measurements since its discovery. I will then discuss the effect of electron-electron interactions. Most of the experiments suggest that in single layer graphene the interactions have only a quantitative effect. However,
recently very high quality graphene heterostructures have been realized and
the experimental measurements conducted on them suggest that in these structures the interactions can drive the electrons into novel spontaneously
broken symmetry ground states. I will present our theoretical study of "hybrid" heterostructures formed by one sheet of single layer graphene and one sheet of bilayer graphene and show that in these structures the spontaneously broken symmetry ground state is 2-fold degenerate with one of the degenerate states analogous to a superfluid chiral state. The chiral nature of one of the degenerate ground states opens the possibility to observe in
graphene heterostructures topologically protected midgap states analogous to Majorana modes.
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