Local non-stoichiometry in superconducting and ferroelectric films of complex oxides

Abstract

By analogy with ferroelectric deposits, in films of deposited high-temperature superconductor YBa₂Cu₃O_7-δ there have been found surface and interface (film-substrate) layers, having a modified composition with respect to the main layer and different charge state of the constituent ions. However, in contrast to the ferroelectric films of BaTiO₃ type, the specific habitus of microcrystals in the YBa₂Cu₃O_7-δ films favours the formation of oriented layers already at the stage of annealing of the initially quasi-amorphous deposits, the stoichiometry of the main layer being preserved. Deterioration of the properties of the films on buffer layers may be explained by changes in the charge state of the film and substrate ions.

Key Words:

• ferroelectric films
• high-Tc superconducting films
• surface and interface layers
• Auger-spectroscopy
• local non-stoichiometry