Lattice spin systems coupled to a compact U(1) gauge field with negative gauge coupling favoring frustration

Abstract

We investigate the phase diagram and nature of the phase transitions of three-dimensional compact lattice Abelian Higgs models with negative gauge coupling. These models describe multicomponent complex scalar fields coupled to a compact U(1) gauge field. Negative gauge coupling favors frustrated plaquette configurations, competing with the tendency of the matter ferromagnetic-like interaction to suppress frustration. Monte Carlo simulations and finite-size scaling analyses of models with one- and two-component scalar fields of unit charge reveal a substantially richer phase structure than at nonnegative gauge coupling. For two components, the O(3) transition line associated with gauge-invariant bilinear ordering extends into the negative-coupling region, and turns into a first-order transition line with decreasing $K$, toward the fully-frustrated $K\to -\infty$ limit. An analogous first-order transition line is also found for the one-component scalar matter with negative gauge coupling. Both one- and two-component models exhibit two additional continuous transition lines at sufficiently large matter coupling. Their energy-cumulant scaling is consistent with three-dimensional Ising and XY critical exponents, suggesting topological transitions in the $\mathbb Z_2$ and XY gauge universality classes, respectively. These results uncover additional phases generated by the competition between matter ordering and dynamical gauge frustration, whose physical characterization remains an open question.