Abstract
An ordered defect structure in superconducting Y-Ba-Cu-O thin films has been characterized by both x-ray diffraction and transmission electron microscopy. The defect structure, which is observed growing epitaxially within the grains of normal structure, has the diffraction characteristics of a distinct phase whose volume fraction can be correlated with changes in film composition. The diffraction characteristics are consistent with an orthorhombic unit cell ( Å, Å) with space group Ammm. These are the characteristics to be expected from a structure in which extra copper-oxygen layers create fault planes, which are inserted at every unit cell in the parent structure. The composition expected for the pure phase is . Preliminary transport measurements on films containing this extra phase are characterized by lower normal-state resistances and a lower Hall constant.
- Received 17 December 1987
DOI:https://doi.org/10.1103/PhysRevB.37.9353
©1988 American Physical Society