Flux creep and flux pinning in layered high-temperature superconductors

For a high-Tc layered superconductor, we study a flux creep when the magnetic field is parallel to the layers (the CU-O planes) and vortices move across them. In a homogeneous material, the pinning of vortices results from their interaction with the layered structure of the superconductor provided the vortex-lattice period is commensurate with the interlayer spacing. The flux-creep activation energy is proportional to j^-1 at small currents due to a large size of the activated vortex bundle.