Novel criticality of Dirac fermions from lattice symmetry breaking

Abstract

We consider the role of spontaneous lattice symmetry breaking in strongly interacting two dimensional Dirac systems. The fermion induced quantum (multi-)criticality is described by Dirac fermions coupled to a dynamical order parameter that is composed of mass and emergent gauge fields. This is illustrated for the example of translational symmetry breaking due to charge-density wave order on the honeycomb lattice. Using a renormalization-group analysis we find that the putative emergent Lorentz invariance is violated. Finally, we identify that topological phase transitions are well described by this effective field theory.