Superconducting properties of YBCO thin films grown on [001] quartz substrates by pulsed laser deposition

Abstract

We present an investigation of the superconducting properties of thin YBa2Cu3O7-x (YBCO) films grown on [001] single-crystalline quartz substrates by pulsed laser deposition (PLD) technique. The growth of YBCO on quartz is challenging due to large crystal lattice mismatch between YBCO and quartz. We obtained highly c-oriented textured films with superconducting transition at about 85 K, transition width of 1 K, and critical current density jc ≈ 104 A cm−2 at 77 K. Analysis of the temperature dependences of the resistivity and current-voltage characteristics has shown the presence of the thermally-assisted flux flow at temperatures above 70 K. From the temperature and magnetic field dependences of critical current, vortex activation energy, U0(H), was estimated for both parallel and perpendicular orientation of magnetic field. Second critical field, Hc2(0), was estimated from extrapolation of the Hc2(T) dependences. The obtained results are an important step towards realization of YBCO thin films on amorphous silica fibers for the third generation (3 G) of the HTS long wire with low losses in alternative current applications.