Oxygen ordering and plane-to-chain electron transfer in YBa2Cu3O7−δ

✍ Scribed by Jeremy K. Burdett

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 782 KB
• Volume: 191
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(92)90660-5

✦ Synopsis

A microscopic model is described which is able to reproduce the observed dependence of T¢ on oxygen stoichiometry for the 123 superconductor YBa2Cu3OT_~. The approach provides a way of estimating the electron hole concentration at the planar copper sites and makes use of the expected location of the d orbital energy levels of copper atoms in various coordination geometries. There are two important features. The fwst is that the presence of isolated oxygen vacancies in a CuO3 chain leads to the generation of excess holes in the x 2-y2 band of the planar copper atoms. Such an effect leads to the 90 K plateau and that part of the 60 K plateau for t~> 0.5. The second is the ineffectiveness of short chains in plane-to-chain charge transfer. This is responsible for the 60 K plateau for t~ < 0.5, and gives insight into to the time-dependent behavior of T¢ for rapidly quenched samples.