Current-voltage characteristics of high-temperature superconducting ceramics with the 'peak effect' in the magnetic field dependence of the transport critical-current density

The experimentally determined current-voltage characteristics of high-Tc superconducting ceramics exhibiting the 'peak-effect' in the magnetic field dependence of the transport critical-current density were described in terms of thermally activated flux creep at grain boundaries; taking into account the collective pinning of intergranular vortices. The peak effect was explained by considering the increase of the intergrain pinning potential at intermediate fields through the interaction of intergranular (Josephson type) vortices and intragranular (Abrikosov) vortices. The magnetic field dependences of the effective pinning potential and of the collective pinning exponent were experimentally determined, and the features of the I-V curves were explained through these dependences.