The polization dependence of x-ray absorption at the oxygen 1s absorption edge in untwinned LuBa2Cu3O7 and PrBa2Cu3O7 single crystal specimens was measured. The hole states of oxygen in the CuO2 plane in PrBa2Cu3O7 locate at higher energy position than those of the oxygen in the CuO2 in superconducting LuBa2Cu3O7, although the hole states of chain sites remain at the same energy position in both Pr123 and Lu123 samples. Although they are mainly of pσ character rather than of pπ and were attributed as an upper Hubbard band, a possibility was pointed out that a trace of pπ character hole states in the CuO2 plane exists in Pr 123. The formation of Zhang-Rice singlet is suppressed by pπ holes in the CuO2 plane on account of the strong Coulomb interaction on an oxygen site.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering