MAGNETIC PENETRATION DEPTH OF TL2BA2CUO6- TC-SIMILAR-TO-SIGMA(0) IN THE OVERDOPED REGION(DELTA )

We report transverse field muon spin rotation experiments carried out on Tl2Ba2CuO6+delta. This system spans the whole overdoped regime, in which T(c) is reduced by excess oxygen doping despite an increasing no rmal state carrier concentration. In the heavily overdoped regime the extrapolated low temperature depolarization rate delta(0) is found to scale linearly with the superconducting critical temperature T(c), sim ilar to the behavior previously observed for other cuprates in the und erdoped regime. In the framework of the clean limit London model, sigm a(0) is-proportional-to lambda-2 is-proportional-to n(s)(0)/m(s), sug gesting that the depression of T(c) by overdoping is associated with a decrease of the superconducting condensate density. This needs to be understood in view of the observed increase in the normal state carrie r density. We discuss some possible explanations for this behavior.