Birefringent breakup of Dirac fermions on a square optical lattice

Malcolm P. Kennett, Nazanin Komeilizadeh, Kamran Kaveh, Peter M. Smith

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25 Scopus citations

Abstract

We introduce a lattice model for fermions in a spatially periodic magnetic field that also has spatially periodic hopping amplitudes. We discuss how this model might be realized with cold atoms in an artificial magnetic field on a square optical lattice. When there is an average flux of half a flux quantum per plaquette, the spectrum of low-energy excitations can be described by massless Dirac fermions in which the usually doubly degenerate Dirac cones split into cones with different "speeds of light." These gapless birefringent Dirac fermions arise because of broken chiral symmetry in the kinetic energy term of the effective low-energy Hamiltonian. We characterize the effects of various perturbations to the low-energy spectrum, including staggered potentials, interactions, and domain-wall topological defects.

Original languageEnglish (US)
Article number053636
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Volume83
Issue number5
DOIs
StatePublished - May 31 2011

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