Josephson junctions in single-crystal YBa2Cu3O7

In this paper it is shown that I-V characteristics of the epitaxial films and unusual magnetic properties of the single crystals may be attributed to the forming on the defects of the plural Josephson junctions. The authors give the estimations of the dielectric gap, of the transparence of the corresponding energy barriers and the characteristic distance between them. The surface superconductivity in the magnetic field is studied. The authors have marked, that non-trivial boundary conditions for high-Tc superconductors lead to the positive curvature on dependence Hc3(T)