Thermoelectric power study on high- Tc Bi-2212 and -2223 oxides intercalated with organic molecules zincphthalocyanine

Abstract

We have systematically studied the behavior of the thermoelectric power S for the high- T c Bi-2212 and -2223 oxides intercalated with organic molecules zincphthalocyanine (ZnPc). The intercalating level x ranges from zero to 0.02 per formula, while T c is degraded from 110 to 85 K for (ZnPc) n Bi-2223 and from 90 to 61 K for (ZnPc) x Bi-2212. It has been observed that the value of S at T = 290 K, S(290), increases with increasing x for both systems. Based on an empirical rule, the carrier concentration n is extracted from S(290). It has been found that n drops sharply for x changing from zero to 0.005, and then decreases gradually with increasing x for both the (ZnPc) x Bi-2212 and -2223 systems. The relation of n with x resembles that of T c with x. Our results suggest that the charge transfer between the ZnPc molecules and the CuO 2 layers plays an important role in the T c-suppression by the ZnPc intercalation. The T c/ T c0− n relations for these samples fall on the same curve, contrast with the previously reported results. This scaling behavior is consistent with the universality of the T c/ T c0− n relation which was proposed previously by Zhang and Sato.