Symmetry, density of doping holes, and Tc in superconducting thallium cuprates

Abstract

Polarized Cu L3 absorption experiments have been made on Tl2Ba2CaCu2O8±δ well-oriented thin films by x-ray spectroscopy. Using a fitting procedure, the doping hole density per copper atom has been measured to be 16%. The results are in agreement with a doping occurring only with the (x,y) symmetry in the [CuO2]∞ planes of these layered structures. Unpolarized XAS experiments have also been conducted on Tl(2:2:0:1), Tl(2:2:1:2), Tl(2:2:2:3), and Tl(1:2:2:3) ceramics with different doping and superconducting properties. The results show that, in the copper monolayer compound, the change in the doping hole density is accompanied by a drastic change of Tc while this effect appears less important in the copper bilayer compounds and even uneffective in the three-layer one. These results show that the doping hole density is a key factor to monitor the superconducting properties and that the number of copper layers also plays an important role.

Source-reported materials — not catalogue approval

Similar papers