Continuous phase transition of a fully frustrated XY model in three dimensions

We have used Monte Carlo simulations, combined with finite-size scaling and two different real-space renormalization group approaches, to study a fully frustrated three-dimensional XY model on a simple cubic lattice. This model corresponds to a lattice of Josephson-coupled superconducting grains in an applied magnetic field $\mathbf{H}=({\mathrm{\Phi }}_0\mathrm{/}{a}^2)(1\mathrm{/}2,1\mathrm{/}2,1\mathrm{/}2)$. We find that the model has a continuous phase transition with critical temperature $T_c = 0.681 J/k_B$,where$J$istheXYcouplingconstant,andcriticalexponents$\alpha/\nu = 0.87 \pm 0.01$,$v/\nu = 0.82 \pm 0.01$,and$\nu = 0.72 \pm 0.07$,where$\alpha$,$v$,and$\nu$ describe the critical behavior of the specific heat, helicity modulus, and correlation length. We briefly compare our results with other studies of this model, and with a mean-field approximation.