Abstract
Thin films of , the parent compound of superconducting oxide with , were prepared by pulsed laser deposition and their structures were investigated by x-ray diffraction analysis. It is known that bulk crystal adopts structures having two kinds of distortions, namely, tilting and breathing of octahedra below 750–800 K. Epitaxial (001) film was grown on MgO (001) substrate at 773 K. In the film, the tilting mode was suppressed at ambient temperature and the structure was cubic with superlattice breathing distortion. This is the experimental realization of having cubic structure with only superlattice breathing distortion at ambient temperature. An electric transport measurement showed that the film is insulating. These results show direct experimental evidence for the idea provided by theoretical studies that the breathing distortion solely can open the gap around the Fermi energy of phase.
- Received 20 June 2008
DOI:https://doi.org/10.1103/PhysRevB.78.132507
©2008 American Physical Society