Strong pinning in YBa2Cu3O7-δ films with SDP-derived amorphous Y2O3 layers

Solution deposition planarisation (SDP), a novel surface modification method, was applied for the enhancement of flux pinning in superconducting thin films for the first time. Solution-derived amorphous Y2O3 films were spin-coated on LaAlO3 (LAO) substrates to modify substrates' surface before sputtering YBa2Cu3O7-delta (YBCO) films. The effect of the concentration of the precursor solution on the surface roughness and superconducting properties of the YBCO films was studied. It is found that the crystallinity and self-field properties of the YBCO films were improved because of the resulting reduction in roughness when the concentration of the precursor solution was properly chosen. As increasing the precursor concentrations, self-field critical current densities (J(c)) were deteriorated and the superconducting properties in magnetic fields were improved. In addition, dislocation densities in YBCO films induced by amorphous Y2O3 were measured and quantitatively calculated. The relationship between the dislocation density and power-law exponent alpha (proportional factor of J(c) similar to H (alpha)) was systematically investigated. The surface planarisation and defect-induced flux pinning behaviour of amorphous Y2O3 films led to potential applications in low cost YBCO coated conductors. (C) 2014 Elsevier B.V. All rights reserved.