INFLUENCE OF DOPANT VALENCY FOR ER IN ERBA2CU3O7-D ON PAIR-BREAKING, HOLE FILLING AND HOLE DOPING MECHANISMS

A systematic study or (Er(1-x)M(x))Ba2Cu3P7-d with M=Hf4+, Pr-3+-->4+, Ca2+ has been caried out with an objective of invesigating the effect of dopant valency and magnetic moment on hole filling, pair breaking and hole doping mechanisms in influencing the superconductivity. It is found that non magnetic Hf-substitution up to x=0.2 shows that the re duction in TS is mainly due to hole filling, whereas the substitution of Pr (up to x=0.2) displays suppression of T-c due to both hole filli ng and pair breaking mechanisms, as Pr possesses fluctuating valence a nd magnetic moment. In the case of non magnetic Ca-substitution, the T -c decreases due to hole doping and pair breaking mechanisms. The comp arative results on these three systems will be discussed in the light of pair breaking. hale doping and hole filling mechanisms through empi rical relations.