Transient moment relaxation in high-temperature superconductors

The decays of the persistent supercurrent have been derived for several characteristic I-V relationships with few sample-dependent parameters. The results are compared with recent short-time flux-creep data in a short ‘‘transient’’ time window (${10}^{\mathrm{-}4–}$ ${10}^2$ s). The results favor the I-V characteristics V∝exp[-(${\mathit{I}}_0$/I${)}^{\mathrm{\mu }}$], as predicted by the collective-pinning and vortex-glass models. However, the μ so obtained is greater than 1, in contrast with that predicted. This may imply a different type of vortex elemental excitation observed in our low-field conditions.