J. Phys. I France
Volume 6, Number 12, December 1996
Page(s) 2265 - 2273
DOI: 10.1051/jp1:1996216
J. Phys. I France 6 (1996) 2265-2273

On a Possible Reason of T $\mathsf{_c}$ Suppression with Oxygen Doping in Tl $\mathsf{_2}$Ba $\mathsf{_2}$CuO $\mathsf{_{6+x}}$

I.F. Schegolev, N.N. Kolesnikov, V.N. Kopylov, T.G. Togonidze and O.M. Vyaselev

Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow District, 142432 Russia

(Received 26 April 1996, revised 23 July 1996, accepted 19 August 1996)

Magnetic susceptibility and 63Cu and 205Tl nuclear spin-lattice relaxation rates have been measured in Tl 2Ba 2CuO 6+x high-temperature superconductor to establish the mechanism of decreasing the transition temperature with oxygen doping. The experiments have revealed the presence of localized paramagnetic centers (LPC) whose concentration grows with increasing oxygen content. These centers can give rise to magnetic scattering of the Cooper pairs and thus be responsible for the $T_{\rm c}$ suppression. This assumption is supported by the pair-breaking effects observed in the NMR Knight shift and relaxation rate behavior in the superconducting state.

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