I-V characteristics of a model vortex glass: A numerical study

We study a hypothetical vortex-glass transition in disordered superconductors in a strong magnetic field, using a three-dimensional generalized Huse-Seung model of coupled, resistively shunted Josephson junctions. Assuming ${\mathit{T}}_{\mathit{g}}$=0.45${\mathit{E}}_{\mathit{J}}$/${\mathit{k}}_{\mathit{B}}$, where ${\mathit{E}}_{\mathit{J}}$ is the coupling energy, the I-V characteristics are found to obey the dynamic scaling relation as proposed by Fisher et al., with critical exponents z≊4 and ν≊0.5 in the range of currents considered, in agreement with mean-field expectations. ν is somewhat smaller than found in recent high-field I-V measurements in superconducting thin films. We conclude that there is probably a vortex-glass transition in this model, with the predicted scaling characteristics, but that our calculations have not yet reached the small-current regime where the asymptotic critical exponents, rather than mean-field values, are expected.