NMR INVESTIGATION ON C60 SUPERCONDUCTORS, CSXRB3-XC60(X=1,2)

Cs-133-NMR was observed in C60 superconductors, CsxRb3-xC60 with x=1 a nd 2. It was found that Cs atoms are intercalated in octahedral inters titial sites of C60 fcc lattice for x=1, while for x=2 in both of the octahedral and tetrahedral interstitial sites. The shift of the Cs-133 -NMR strongly suggested that the 69 electron of Cs atom is fully ioniz ed and conduction electrons are mainly on the C60 sites. C-13-NMR was observed to study electronic states at C60 sites. It showed a monotoni c increase of the superconducting transition temperature, Tc, with inc reasing Fermi level density of states, N(E(f)), at carbon sites, where N(E(f))-2 was assumed to be proportional to C-13 spin-lattice relaxat ion time T1 times temperature T: N(E(f))-2 is-proportional-to T1T.