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

TL;DR

This paper introduces a lattice model for realizing quartic semi-Dirac fermions with unique anisotropic dispersion, stabilized by short-range interactions, advancing understanding of exotic quasiparticles in two-dimensional materials.

Contribution

It presents a novel tight-binding lattice model with anisotropic hopping and short-range interactions to stabilize quartic semi-Dirac fermions in 2D.

Findings

Successfully models quartic semi-Dirac dispersion in 2D

Shows short-range interactions stabilize the quartic phase

Identifies instability towards Dirac or quadratic semi-Dirac phases without interactions

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.