13C NMR and static magnetic susceptibility in C60 superconductors : Possible influence of Kondo impurity

The static spin susceptibility, xs SQ and xs NMR , in C60 superconductors K3C60 and Rb3C60 was studied using a dc superconducting quantum interference device magnetometer and C NMR. We found that xs SQ has a peculiar temperature ~T! dependence behaving as (12CT) with a positive constant C;(1310) deg, contrary to the almost T independent xs NMR . These observations indicate a possibility that there exist Kondolike impurities, whose Kondo temperature is ;500 K and whose content is ;0.001 spins per carbon. On the basis of these studies, the lattice constant dependence of the intrinsic spin susceptibility was established to be dxs /da05(5.760.4)310 24 emu/mol C60 /A in A3C60 superconductors where A is an alkali metal. @S0163-1829~98!02241-3#