A model for vortex depinning and motion is presented, which takes into account the inhomogeneity of a real type-II superconducting material. The model is based upon a mechanism, in which the flux-line lattice is depinned by a synchronous shear around the vortices, which are too strongly pinned to be broken. In contrast to the classical flux-line shear model, variations in the vortex-vortex interactions are allowed. The applicability of this model is demonstrated by evaluating the real resistive data for the ceramic superconductor ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_7$ in the mixed state. The simulated data agree very well with experimental observations. An Arrhenius-like temperature dependence of the resistance at the transition to the superconducting state is evaluated. The shape of the simulated voltage-current curves, the field and temperature dependence of the volume pinning force, and the position of the peak in the volume pinning force resemble experimental data. Furthermore, the presence of a reversible regime close to the transition to the normal state follows automatically from the model.

• Received 27 January 1992

DOI:https://doi.org/10.1103/PhysRevB.46.3076