Thin HTS film of a YBCO with the frozen strains

Strained HTS YBa2CuO7-d films of thickness more than the critical one were deposited on LaAlO3 substrates (100) by the laser ablation method. Strains were frozen in the films by rapid cooling just after the laser deposition. These films, which we call the 'frozen-strain films', have a very surprising temperature dependence of critical current density: it has a characteristic minimum in the temperature range of 55-57 K. The critical current density at 77 K is suppressed from 106 A/cm2 down to 104 A/cm2 at 77 K and below, but these films are very stable at thermocycling from 300 K to the nitrogen boiling temperature. The scanning tunnel microscope study suggests that strained domains are formed in these films. The domain sizes reduce with increasing strains and average between 1and 2.4 mm. Magnetic field penetration into the frozen-strain films differs from mono and granular films. This also suggests the macroscopic structurization of the 'frozen-strain films'