Structural properties of Pb(Zr0.53Ti0.47)O3/YBa2Cu3O7-δ heterostructures on SrTiO3 substrates

Abstract

The structures of ferroelectric Pb(Zr0.53Ti0.47)O3 and high-Tc YBa2Cu3O7−δ superconductor integrated films on (0 0 1) SrTiO3 substrate prepared by the r.f./d.c. magnetron sputtering method have been studied by X-ray grazing incidence reflectivity, diffuse scattering and high-resolution X-ray diffraction methods combined with atomic force microscopy (AFM) and SEM techniques. The results of high-resolution X-ray diffraction show that the quality of Pb(Zr0.53Ti0.47)O3 improved as the thickness increased. On the other hand, the crystalline quality of YBa2Cu3O7−δ deteriorated and the superconducting transition temperature, Tc, decreased as the thickness of Pb(Zr0.53Ti0.47)O3 increased. The strain state was similar for different thickness samples and the lattice mismatch strain in the Pb(Zr0.53Ti0.47)O3 layer was almost totally relaxed. The root mean square (r.m.s.) roughness at Pb(Zr0.53Ti0.47) O3/YBa2Cu3O7−δ interface was determined to be about 1.7±0.3 nm by X-ray specular reflectivity. The r.m.s. roughness at the surface of Pb(Zr0.53Ti0.47)O3/YBa2Cu3O7−δ bilayer samples was about 1.5 to 2.0±0.3 nm which was larger than that of YBa2Cu3O7−δ single-layer sample measured by both X-ray specular reflectivity and AFM methods. The results from AFM and SEM show that the morphological characteristics of the Pb(Zr0.53Ti0.47)O3 layer surface were large grains covering about 10% in area distributed on a fine-grained matrix. © 1998 Chapman & Hall