Scientific Colloquium
April 24, 2009

"Graphene: Exploring Carbon Flatland"

Graphene is an atomically two-dimensional material which is described by
ultra-relativistic quantum mechanics.  I will review progress toward graphene-based electronic devices
based on both conventional ideas and on the properties of novel broken
symmetry states which might be realized when two graphene layers are
separated by a nm scale dielectric barrier.  The absence of a mass (a gap)
in ultra-relativistic quantum mechanics presents a challenge in adopting
conventional device physics to this material.  I will discuss progress in
inducing gaps by making narrow graphene ribbons or by placing graphene
bilayers in external electric fields.  The broken symmetry which might be
realized in systems with two separated graphene layers is one in which phase
coherence is established spontaneously between separate layers.  These
states are counterflow superfluids in which current can flow in opposite
directions in the two layers without dissipation.  I will discuss some ideas
for electronic devices based on the properties of these unusual superfluids.

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