Microscopic lattice model for quartic semi-Dirac fermions in two dimensions

Abstract

We propose a lattice model for the realization of exotic quartic semi-Dirac fermions, i.e. quasiparticles exhibiting a dispersion with quartic momentum dependence in a given direction, and a linear dependence in the perpendicular direction. A tight binding model is employed, allowing for hopping between up to fourth nearest neighbors and anisotropic hopping parameters. In addition, we introduce short range electron-electron interactions which are necessary to stabilize the quartic semi-Dirac phase. Without interactions, or in the presence of long range correlations, the lattice is unstable towards formation of either anisotropic Dirac cones, or simple (quadratic) semi-Dirac phase.