Magnetic resonance evidence for metallic conduction mechanism in new, highly conducting polyaniline

Summary form only given. Polyaniline doped with camphor sulfonic acid (PANI-CSA) has shown to yield a material which, after recrystallization from meta-cresol solutions, exhibit a temperature independent magnetic susceptibility down to 50K. Below 50K, a Curie-like contribution to the electronic susceptibility (X=C/T) is observed, indicative of singly occupied states at the Fermi energy. We conclude from this crossover that the intrasite electron-electron interaction parameter, U, is 50-60K (4-5 meV). From the spin glass transition at around 10K the average spin-spin coupling (random in sign) is estimated to be 0.5-1 meV. We also report /sup 13/C NMR experiments on uniformly /sup 13/C enriched PANI-CSA in which the /sup 13/C spin-lattice relaxation rates are shown to obey the Korringa relation for relaxation via the hyperfine coupling to conduction electrons. This first observation of Korringa relaxation in a conducting polymer provides strong evidence for a polaronic, metallic conduction mechanism in this material. Two-dimensional spin exchange experiments are also reported.