ON A POSSIBLE REASON OF T-C SUPPRESSION WITH OXYGEN DOPING IN TL2BA2CUO6+X

Magnetic susceptibility and Cu-63 and Tl-205 nuclear spin-lattice rela xation rates have been measured in Tl2Ba2CuO6+x high-temperature super conductor to establish the mechanism of decreasing the transition temp erature with oxygen doping. The experiments have revealed the presence of localized paramagnetic centers (LPC) whose concentration grows wit h increasing oxygen content. These centers can give rise to magnetic s cattering of the Cooper pairs and thus he responsible for the T-c supp ression. This assumption is supported by the pair-breaking effects obs erved in the NMR Knight shift and relaxation rate behavior in the supe rconducting state.