Specific heat and electron photoemission of Pb- and Bi- doped Tl-(Ba,Sr)-Ca-Cu-O (1223) high- temperature superconductors

Specific heat of Tl0.58Pb0.4Sr1.6Ba0.4Ca2Cu3Oy, Tl0.79Bi0.25 Sr1.6Ba0.4Ca2Cu3Oy and Tl0.74Bi0.3Sr1.8Ba0.2Ca2Cu3Oy has been measured and the electronic specific heat coefficient g and the specific heat jumps DC at TC have been calculated. The DC ' s are about three times smaller than for the YBa2Cu3Ox samples. The core level and valence band spectra for Tl0.58Pb0.4Sr1.6Ba0.4Ca2Cu3Oy have been detected at room, at liquid nitrogen and at 125 K temperatures. The Fermi edge has not been observed though pronounced changes of the valence band shapes have been registered. This is most likely due to the larger anisotropy of electronic band structure of thallium samples in comparison to the yttrium superconductors.