抄録
Knight shift, K, nuclear spin-lattice relaxation time, T1, and spin echo decay time, T2, at various sites have been measured for SnMo6Se8, PbMo6Se8 and PbMo6S8. K shows little change in the superconducting state from the value of normal state, which implies the remaining of the spin susceptibility of conduction electrons in the superconducting state. The density of state at the Fermi level is evaluated from T1 in the normal state. The agreement of the results with the recent band calculation is satisfactory except for Se site, where the experimental result suggests larger density of state. The superconducting energy gaps are about 3.5 kBTC(0) for all sites. Not only d-electrons of Mo but s- or p-electrons of Sn, Pb and Se atoms take part in the superconductivity. T2 for all sites decreases with the onset of the superconductivity. This may be attributed to the conversion of the indirect coupling between like spins to the unlike ones effectively owing to the field inhomogeneity due to vortices.
