Interaction of Abrikosov vortex with grain boundaries near Hc1.: I.: Potential barriers in polycrystalline high-Tc superconductors

The effects of the interaction of an Abrikosov vortex with grain boundaries is investigated in the framework of a model in which the vortex, grain, and grain boundaries are treated oil a unified basis. An exact solution is found for the vortex-laminar model. New types of potential barriers for the entry of a vortex into a superconducting polycrystalline are predicted. Like the traditional Bean-Livingston barrier, the value of the "edge" barrier in these materials depends on the value of the external field, but it also depends oil the normalized grain size, the intensity of the coupling between grains, the anisotropy, and the degree of "specularity" (smoothness) of the material in the case of ultrafine-grained superconducting materials. (C) 2005 American Institute of Physics.