In-situ low pressure oxygen annealing of YBa2Cu3O7−δ single- and multilayer systems

✍ Scribed by G. Ockenfuβ; R. Wördenweber; T.A. Scherer; R. Unger; W. Jutzi

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 388 KB
• Volume: 243
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(94)02449-9

✦ Synopsis

Optimized NdGaO3/YBa2Cu307_~ multilayers grown by various techniques usually suffer from reduced superconducting transition temperatures due to oxygen deficiency in the superconducting layer. We examined different post-deposition processes for in-situ and ex-situ oxygen treatment of sputter-deposited YBa2Cu3OT_ ~ single-and NdGaO3/YBa2Cu3OT_ ~ bilayers. The only procedure which reproducibly recovered the superconducting properties for YBCO films covered with a dense NdGaO3 top layer, was found to be a low-pressure procedure (typically < 250 Pa) at the temperature of the structural transition from the tetragonal (non-superconducting) to the orthorhombic (superconducting) perovskite structure in activated oxygen. Furthermore, this procedure is advantageous for single-layer YBCO or other YBCO multilayer systems. The optimum condition for the oxygen treatment was determined to be 200 Pa and 540°C, yielding transition temperatures T c >/90 K and values for the ratio of the resistivities at 300 K and 100 K of 3.2.