The doping dependence of the superconducting condensate density, n_{ s}^{ o}, has been studied by muon-spin-rotation for Y_{ 0.8}Ca_{ 0.2}Ba_{ 2}(Cu_{ 1-z}Zn_{ z})_{ 3}O_{ 7-\delta} and Tl_{ 0.5-y}Pb_{ 0.5+y}Sr_{ 2}Ca_{ 1-x}Y_{ x}Cu_{ 2}O_{ 7}. We find that n_{ s}^{ o} exhibits a pronounced peak at a unique doping state in the slightly overdoped regime. Its position coincides with the critical doping state where the normal state pseudogap first appears depleting the electronic density of states. A surprising correlation between n_{ s}^{ o} and the condensation energy U_{ o} is observed which suggests unconventional behavior even in the overdoped region.
Categories: cond-mat.supr-con