Transport properties of high-temperature superconductors: Surface vs bulk effect

We investigate surface-related transport properties of high-temperature superconductors. We find the mean vortex velocity under applied transport current determined by the activation energies for vortex penetration and exit through the Bean-Livingston barrier. We determine the current distribution between the surfaces of superconductor and the field and current dependencies of the transport activation energies. For a three-dimensional superconductor the transport activation energy, Uₛ3D, is found to decrease with the external field, H, and transport current, J, as Uₛ3D∝H^-1/2 and Uₛ3D∝J^-1/2, respectively. In the quasi-two-dimensional compounds, Uₛ2D decays logarithmically with field and current. The interplay between the surface and the bulk contributions to the transport properties, such as current-voltage characteristics, is discussed.