Superconducting properties of binary rare-earth HoREBCO thin films prepared by pulsed layer deposition

The superconducting properties of REBa₂Cu₃O_y (REBCO or RE123, RE = rare earth elements) coated conductors could essentially depend on the rare earth elements, which could be the premise of all potential superconducting applications. In this paper, Ho_0.75RE_0.25Ba₂Cu₃O_7-σ (HoREBCO, RE = Dy, Er, Yb) high temperature superconducting films were fabricated successfully by a reel-to-reel pulsed laser deposition (PLD) system for the first time. By replacing Ho elements with heavy rare earth elements in a certain mole ratio, the critical currents of the HoREBCO superconducting films were improved significantly compared with pure HoBCO films. The lattice distortions are considered as the determinative factors of the changes. The replacement of Ho atoms by Dy, Er or Yb also influenced the structure and the surface morphology of the superconducting films. The decrease of the lattice constant in HoREBCO superconducting film and the variation of the interatomic force play the decisive role in the improvement of the superconducting property.