Y. Maniwa et al., C-13 NMR AND STATIC MAGNETIC-SUSCEPTIBILITY IN C-60 SUPERCONDUCTORS -POSSIBLE INFLUENCE OF KONDO IMPURITY, Physical review. B, Condensed matter, 58(17), 1998, pp. 11603-11606
The static spin susceptibility, chi(s)(SQ) and chi(s)(NMR), in C-60 su
perconductors K3C60 and Rb3C60 was studied using a de superconducting
quantum interference device magnetometer and C-13 NMR. We found that c
hi(s)(SQ) has a peculiar temperature (T) dependence behaving as (1 - C
T2) with a positive constant C similar to(1 x 10(-6)) deg(-2) contrary
to the almost T independent chi(s)(NMR). These observations indicate
a possibility that there exist Kondo-like impurities, whose Kondo temp
erature is similar to 500 K and whose content is similar to 0.001 spin
s per carbon. On the basis of these studies, the lattice constant depe
ndence of the intrinsic spin susceptibility was established to be d ch
i(s)/da(0) =(5.7+/-0.4) x 10(-4) emu/mol C-60/Angstrom in A(3)C(60) su
perconductors where A is an alkali metal. [S0163-1829(98)02241-3].