MAGNETIC PENETRATION DEPTH OF TL2BA2CUO6-TC-INFINITY-SIGMA-O IN THE OVERDOPED REGION(DELTA)

We report transverse-field muon-spin-rotation experiments carried out on T12Ba2CuO6+delta. This system spans the whole overdoped regime, and T(c) is reduced by excess oxygen doping, which increases the normal-s tate carrier concentration. In the heavily overdoped regime sigma(0) i s found to scale linearly with the superconducting critical temperatur e T(c), similar to the behavior previously observed for other cuprates in the underdoped regime. However, for the overdoped region one has t o explain the reduction of sigma0, thus the increase of the magnetic p enetration depth lambda, in spite of an increasing normal-state carrie r concentration. We discuss some possible explanations for this behavi or.