We suggest a model of mismatched interface and calculate its energy in order to describe formation of threading edge dislocations by the mechanism of rotational relaxation of interface stresses. The model takes into account strongly layered perovskite structure of high-temperature superconductors. We have shown that rotational relaxation occurs due to finite size of clusters and to non-equilibrium effect of the film growth. We have predicted the subgrain size and the expected rotation of domains depending on the lattice mismatch. The computed values are consistent with the observed YBCO film nanostructure.

The model of single vortex escape from extended linear defect and subsequent vortex dynamics under the Lorentz force action in a rather thick (d > 2λ) 3D anisotropic superconductor is developed. We consider the case of parallel c-oriented linear defects as well as the case of equidistant linear row of such kind of defects, which represents the dislocation model of low-angle [001] tilt grain boundary in HTS films and bicrystals. The suggested model based on the classical mechanics approach allows to describe behavior of an elastic vortex string in the potential well of linear defect and under the action of Lorentz force on its end within the Meissner current carrying layer and to determine the depinning critical current density at low magnetic fields and temperatures.

We have studied nanostructure, electric transport and microwave properties of HTS YBa2Cu3O7-δ films prepared by PLD on LaAlO3 single crystal substrates using targets doped with BaZrO3. Two essentially different types of nanoparticles are revealed by HREM: “nanopancakes” and “nanorods”. Tiny nanopancakes are 1-4 nm in ab-plane and only few atomic layers thick. Nanopancakes are surrounded with deformed area and numerous dislocations. Such nanoparticles seem to be responsible for jc enhancement. Nanopancakes evolve to much wider and longer nanorods at higher substrate temperatures and/or slower deposition. There are no dislocations around nanorods. Elastic strains are avoided due to slight inclination of the c-axis. Dislocations around nanopancakes are suggested to be additional flux pinning centers and retard thermally activated relaxation of the dislocation nanostructure.