Graphene with geometrically induced vorticity.
At half filling, the electronic structure of graphene can be modeled by a pair of free two-dimensional Dirac fermions. We explicitly demonstrate that in the presence of a geometrically induced gauge field an everywhere-real Kekulé modulation of the hopping matrix elements can correspond to a nonreal Higgs field with nontrivial vorticity. This provides a natural setting for fractionally charged vortices with localized zero modes. For fullerenelike molecules we employ the index theorem to demonstrate the existence of six low-lying states that do not depend strongly on the Kekulé-induced mass gap.
School of Physics and Astronomy, University of Leeds, Leeds, United Kingdom. j.k.pachos@leeds.ac.uk
Jiannis K
JK
Pachos
Michael
M
Stone
Kristan
K
Temme