Fig. 1: Magnetic phases of the 2D antiferromagnetic Heisenberg model on a bilayer honeycomb lattice.
From: Cavity-renormalized quantum criticality in a honeycomb bilayer antiferromagnet
Depending on the ratio between the interlayer coupling JD (bold, red) and intralayer coupling J (thin, gray), the magnetic ground state either forms a Néel-type antiferromagnetic order or interlayer singlet dimers, breaking no symmetries. At the phase boundary there is a quantum critical point of the three-dimensional O(3) universality class. Here we consider \({J}_{{{{{{{{\rm{D}}}}}}}}}\approx {J}_{{{{{{{{\rm{D}}}}}}}}}^{c}\), the critical value corresponding to that critical point, and a coupling to a cavity mode described by the quantum vector potential \(\hat{{{{{{{{\bf{A}}}}}}}}}\), linearly polarized along one of the in-plane bond directions.
