Valence Electronic-Structure of Thallium-Compound High-Temperature Superconductors

We used photoemission spectroscopy with synchrotron radiation to investigate the electronic structure of eight different thallium cuprates: pure Tl2.2Ba2CuO(y), Ce-doped Tl2.2Ba(2-x)Ce(x)CuO(y) (x = 0.1, 0.15, 0.2) and Tl2Ba2CeCu3O(y), and Zr-doped Tl2Ba(2-x)Zr(x)CuO(y) (x = 0.005, 0.05). The material are high-temperature superconductors, except one of the Tl2.2Ba2CuO(y) samples. The study included an investigation of the valence-electron density of states, and a detailed analysis of the Fermi edge at room temperature. No departures from the Fermi-liquid picture were observed.