Graphene
Graphene, a single atom thick sheet of carbon atoms arranged in a honeycomb lattice, is the first truly two-dimensional material available for use in experiments. Although graphene has been known for decades to be the buildling block of graphite, and its electronic structure was first derived in 1947 by P. R. Wallace, this remarkable material was first isolated only in 2004 by A. K. Geim and K. S. Novoselov, who were awarded the 2010 Nobel prize in physics for this accomplishment.
In our group, research on graphene has focused on the underlying electronic structure and associated electronic transport and thermodynamic properties of bilayer [1] and ABA-stacked trilayer graphene [2]. These are studied via measurements of the electronic compressibility-- which gauges how strongly the electron gas responds to external electric fields-- as well as measurements of the zero and high magnetic field electronic transport-- including the unusual manifestation of quantum Hall effects in graphene. In bilayer graphene, we found clear evidence that the band dispersions are indeed hyperbolic in form, a clear departure from the parabolic dispersions common to most semiconductors. In ABA trilayer graphene, we have found strong evidence for a semimetallic band overlap, making ABA trilayers the thinnest multilayer graphene to have an electronic structure that begins to resemble that of the parent compound, graphite.
Our current research is focused on accessing the electronic properties of pristine graphene, by fabricating devices in which disorder plays a minimal role.
[1] E. A. Henriksen and J. P. Eisenstein, Measurement of the electronic compressibility of bilayer graphene, Phys. Rev. B 82, 041412(R) (2010). Download at: PRB Rapid or arXiv
[2] E. A. Henriksen, D. Nandi, and J. P. Eisenstein, Quantum Hall Effect and Semimetallic Behavior of Dual-Gated ABA-Stacked Trilayer Graphene, Phys. Rev. X 2, 011004 (2012). Download at: Phys. Rev. X or arXiv