THE ELECTROSTATIC MECHANISM OF ABRIKOSOV VORTEX PINNING AT CHARGED POINT-DEFECTS AND EDGE DISLOCATIONS IN HIGH-TC SUPERCONDUCTORS

The electrostatic mechanism of flux pinning at point defects and dislocations is discussed. The essence of this mechanism is that at the transition from normal to superconducting state the Cooper pair creation results in the reduction of the static electron polarizability of the metal, with the consequence that the shielding of charged defects decreases, the shielding radius increases, and the absolute value of the negative electrostatic energy of shielding electrons in the charge field reduces; i.e. the full energy of electrons in the S-phase is higher than in the N-phase. The critical current determined by the pinning at dislocations has been estimated to reach 10(-6) A cm2 for high T(c) superconductors, which agrees with experimental results for epitaxial quasi-single crystal films.