The first superconducting thin film oxycarbonates coherent intergrowth of several members of a new structural series (CaCuO 2) m (Ba 2CuO 2CO 3) n

• Published in: Physica. C, Superconductivity Superconductivity, 1995, Vol.241 (1), p.158-166
• Main Authors: Allen, J.L., Mercey, B., Prellier, W., hamet, J.F., Hervieu, M., Raveau, B.
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Laser deposition; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 0921-4534; 1873-2143
• DOI: 10.1016/0921-4534(94)02356-5

Superconducting thin films of copper oxycarbonates have been synthesized for the first time using laser ablation. The resistance measurements show a broad transition with T c onset ranging from 80 to 100 K and zero resistance below 60 K. Magnetic measurements indicate diamagnetism below 58 K in the best film. The ED and HREM studies show that these new oxycarbonates are tetragonal with a ∼ a p and c ∼ ( m + 2) × a p, and that the films consist of an intergrowth of serveral members of a family with the general composition (CaCuO 2) m (Ba 2CuO 2CO 3) n . The main member that forms the matrix, Ba 2Ca 3Cu 4CO 3O 8 ( m = 3; n = 1), consists of double layers of CuO 4 groups sandwiched by pyramidal copper layers and interconnected with layers of CO 3 groups. In a general way, the different members of the series can be described as the intercalation of layers of carbonate groups in the infinite-layer structure CaCuO 2. The origin of superconductivity and the relationships with bulk “BaCaCu” oxycarbonates that are prepared at high pressure are discussed.