Current-voltage scaling of a Josephson-junction array at irrational frustration

Numerical simulations of the current-voltage characteristics of an ordered two-dimensional Josephson-junction array at an irrational flux quantum per plaquette are presented. The results are consistent with a scaling analysis that assumes a zero-temperature vortex-glass transition. The thermal-correlation length exponent characterizing this transition is found to be significantly different from the corresponding value for vortex-glass models in disordered two-dimensional superconductors. This leads to a current scale where nonlinearities appear in the current-voltage characteristics decreasing with temperature T roughly as T² in contrast with the T³ behavior expected for disordered models.