Magnetic penetration depth of 585-01585-01585-01: Tc ∼ σ₀ in the overdoped region

Abstract

We report transverse field muon spin rotation experiments carried out on Tl₂Ba₂CuO_6+δ. This system spans the whole overdoped regime, in which T_c is reduced by excess oxygen doping despite an increasing normal state carrier concentration. In the heavily overdoped regime the extrapolated low temperature depolarization rateσ(0) is found to scale linearly with the superconducting critical temperature T_c similar to the behavior previously observed for other cuprates in the underdoped regime. In the framework of the clean limit London model,σ(0) ∝λ ⁻² ∝ n _s (0)/m ^* _s , suggesting 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 carrier density. We discuss some possible explanations for this behavior.