Structural and superconducting properties of YBa2Cu3O7-delta/PrBa2Cu3O7-delta

Using in situ pulsed laser deposition, we grew high-temperature superconducting multilayer films of YBa2Cu3O7-delta (YBCO)/PrBa2Cu3O7-delta (PrBCO) on LaAlO3 (100) and SrTiO3 (100) substrates. The modulation wavelength ranged from 24 Angstrom to 127 Angstrom. The thickness ratios of the films were 1:1, 1:3, and 1:5 for YBCO to PrBCO. We characterized the films with theta-2 theta X-ray diffraction, atomic force microscopy (AFM), scanning electron microscopy (SEM), and Rutherford backscattering spectrometry (RES) including ion-beam channeling. The films showed a strong texture along the c-axis normal to the substrate plane, and a high chemical order of superlattices with a coherence length of about 450 Angstrom. The critical temperature T-c was 85 K for YBCO, 70 K for both (YBCO(5 uc)/PrBCO(5 uc))(N)/LaAlO3 (100) and (YBCO(3 uc)/PrBC0(3 uc))N/LaAlO3 (100) films. The (YBCO(1 uc)/PrBCO(3 uc))(N)/LaAlO3 (100) film exhibited T-c=22 K, and its resistivity revealed a strong semiconducting behavior as the temperature varied.