Cavity-renormalized quantum criticality in a honeycomb bilayer antiferromagnet

We investigate the fate of a quantum critical dimerized antiferromagnet when it is coupled to a quantized high-frequency cavity field. Using unbiased Quantum Monte Carlo simulations, we compute the scaling behavior of the magnetic structure factor and other observables. While the position and universality class are not changed by a single cavity mode, the critical fluctuations themselves obtain a sizable enhancement, scaling with a fractional exponent that defies expectations based on simple perturbation theory. The scaling exponent can be understood using a generic scaling argument, based on which we predict that the effect may be even stronger in other universality classes.

Our microscopic model is based on realistic parameters for 2D magnetic materials and the effect may be within the range of experimental detection.