Multiple-nuclei NMR investigations on fullerides that contain sodium, Na2AC60 (A=K,Rb,Cs), with a simple-cubic structure are reported. The density of states at the Fermi level vs lattice constant correlation was determined. The superconductivity in Na2AC60 connot be described by the same parameters as those of the other A3C60 superconductors within the Bardeen-Cooper-Schrieffer theory. We find that structural imperfection plays an important role in determining the electronic states and onset of superconductivity in Na2AC60. Evidence for the orientational ordering transition was also found with Na23 NMR for A=Cs, Rb, and K.
ASJC Scopus subject areas
- Condensed Matter Physics