SUPPRESSION OF SUPERCONDUCTIVITY IN ER1-XCAXBA2CU3OY BY HOLE DOPING AND PAIR-BREAKING

Ca-substituted (Er1-xCax)Ba2Cu3Oy superconductors have been prepared u nder identical conditions and the temperature dependence of the electr ical resistivity of samples are measured (0 less than or equal to x le ss than or equal to 0.3). The oxygen content of the samples (x = 0-0.3 ) were determined by the iodometric method. The interrelationship betw een the superconducting transition temperature T-c and the variation o f oxygen content has been discussed in terms of the Cu valence. The ob served reduction of T-c with increasing x in (Er1-xCax)Ba2Cu3Oy suppor ts the view that magnetic pair breaking by local moments and hole dopi ng contribute substantially to the suppression of the superconductivit y by Ca.