SUPERCONDUCTIVITY IN CONDUCTING POLYMER FULLERENCE COMPOSITE DOPED BY ALKALI-METAL

Superconductivity in poly(3-alkylthiophene)-C-60 composite (PAT-C-60) is found upon doping by potassium from vapor phase. The superconducting (SC) transition at T-c=17 K is detected by superconducting quantum interference device (SQUID), which showed 0.8% of SC fraction for C-60 content of 5 mol%. An exceptionally strong low-field microwave absorption (LFMA) implies the existence of granular SC phase. A rather small hysteresis of LFMA indicates the important role of the Josephson weak link network, probably formed between SC KxC60 clusters separated by conductive K(x)PAT barriers. ESR of PAT(C-60)(y)K-x composite shows two types of lines: one from negative polarons P- in PAT chains, and another assigned to KxC60 clusters and C-60(1-) radical.