NMR-STUDIES OF SUPERCONDUCTING NA(2)AC(60) (A=CS, RB, AND K) FULLERIDES

Multiple-nuclei NMR investigations on fullerides that contain sodium, Na(2)AC(60) (A=K,Rb,Cs), with a simple-cubic structure are reported. T he density of states at the Fermi level vs lattice constant correlatio n was determined. The superconductivity in Na(2)AC(60) connot be descr ibed by the same parameters as those of the other A(3) C-60 supercondu ctors within the Bardeen-Cooper-Schrieffer theory. We find that struct ural imperfection plays an important role in determining the electroni c states and onset of superconductivity in Na(2)AC(60). Evidence for t he orientational ordering transition was also found with Na-23 NMR for A =Cs, Rb, and K.