Thermally assisted vortex diffusion in layered high-Tcsuperconductors

Using a dynamical equation we study the voltage-current characteristics of high-${\mathit{T}}_{\mathit{c}}$ superconductors below the critical temperature ${\mathit{T}}_{\mathit{c}}$ due to thermally assisted vortex motion in a sinusoidal pinning potential, which is a good approximation to the intrinsic pinning caused by the layered structure when the magnetic field is parallel to the layers. The power-law I-V characteristics and continuous crossover from flux creep to flux flow in high-${\mathit{T}}_{\mathit{c}}$ superconductors can be interpreted in a natural way.