The doping dependence of the critical current density, $J_{ c}$, was measured in a series of high quality c-axis oriented ${ \rm Bi_2Sr_2CaCu_2O_{ 8+\delta}}$ thin films. For each doping level we measured the temperature dependence of $J_{ c}$. We find that all samples have the same temperature dependence, but the critical current at zero temperature, $J_{ c}(0)$, has a non-trivial doping dependence with a maximum at a unique doping level in the overdoped side of the superconducting dome.
Categories: cond-mat.supr-con