TRANSITION FROM STRONG TO WEAK-COUPLING REGIME WITH LOWERING T-C IN TL2BA2CUO6+X

Using Tl-205 NMR, the changes in electronic properties in the normal a nd superconducting state of the Tl2Ba2CuO6+X compound associated with variation of T-c, are studied in samples with T-c = 30, 100, and 115K. Decreasing T-c with oxygen doping is shown to be associated with the growth of the static electron spin susceptibility and with lowering th e Delta/T-c ratio (Delta is superconducting gap). This effect indicate s to the corresponding weakening of coupling regime.