Dependence of the oxygen isotope effect upon hole density in Bi2Sr2Ca1−xYxCu2O8+δ and Y1−xCaxBa2Cu4O8

✍ Scribed by H.J. Bornemann; D.E. Morris; H.B. Liu; P.K. Narwankar

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 738 KB
• Volume: 191
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(92)90650-2

✦ Synopsis

We have investigated the dependence of the oxygen isotope effect on the hole density in the high-T~ cuprates Bi2Sr2CaCu2Os and YBa:Cu~Os. The hole density n was varied by partial replacement of Ca by Y (hole acceptor) in BizSr2CaCu2Os, and by partial replacement of Y by Ca (hole donor) in YBa2Cu4Os. In both cases the dopant was introduco.d into the eightfold coordinated site between the two CuO2 sheets. The hole concentration could be varied to reach maximum T¢ and upon further doping T~ decreased. The oxygen isotope effect ao was found to be strongly correlated to n and T~. When n is optimized to give maximum T~, ao is very small, dose to zero and ~o increases rapidly when n is either less than or greater than the optimum.