Y. Maniwa et al., NMR-STUDIES OF SUPERCONDUCTING NA(2)AC(60) (A=CS, RB, AND K) FULLERIDES, Physical review. B, Condensed matter, 52(10), 1995, pp. 7054-7057
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.