C-13 NMR HYPERFINE COUPLINGS, T-1 ANISOTROPY, AND KORRINGA RELATIONS IN RB2CSC60 - SEARCH FOR EFFECTS OF STRONG CORRELATION

Initial considerations lead one to suspect that effects of strong corr elation might be present in the alkali fulleride superconductors. We r eport direct measurements of C-13 T-1 anisotropy at 80 K in Rb2CsC60 a nd compare, in the context of the Korringa relation, the inferred spin -dipolar contribution to 1/T-1 with the widths of the measured powder pattern line shape. The results demonstrate that the Korringa relation , valid in the limit of noninteracting electrons, holds in this case. Taken together with other normal-state NMR behavior this result makes important effects of strong correlation appear unlikely.