Suppression of superconductivity in the (Er_1-x-yPr_xCa_y)Ba₂Cu₃O_{7- delta}(O<or=(x, y)<or= 0.3) system

Abstract

Pr- and Ca-substituted (Er1-x-yPrxCay)Ba2Cu3O7- delta superconductors have been prepared under identical conditions and characterized according to resistivity and AC susceptibility measurements. The observed reduction of Tc with x in (Er1-xPrx)Ba2Cu3O6.90 for 0<or=x<or=0.3 can be described by an empirical relation which incorporates the filling (or localization) of mobile holes in the CuO2 planes and magnetic pair breaking by local moments. In a similar way, the observed lowering of Tc with increasing y in (Er1-yCay)Ba2Cu3O7- delta provides convincing evidence that superconducting electron pair breaking and hole doping are responsible for the suppression of superconductivity by Ca.