Superconductivity in conducting polymer/fullerence composite doped by alkali metal

Abstract

Superconductivity in poly(3-alkylthiophene)-C60 composite (PAT-C60) is found upon doping by potassium from vapor phase. The superconducting (SC) transition at Tc=17 K is detected by superconducting quantum interference device (SQUID), which showed 0.8% of SC fraction for C60 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 KxPAT barriers. ESR of PAT(C60)yKx composite shows two types of lines: one from negative polarons P‒ in PAT chains, and another assigned to KxC60 clusters and C160‒ radical. © 1995 The Japan Society of Applied Physics.