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. copyright 1996 The American Physical Society