³⁹K-NMR observation of temperature-dependent spin susceptibility in K₃C₆₀

³⁹K-NMR spectra of superconducting fulleride K₃C₆₀ are obtained in the normal state. The ³⁹K-NMR shifts of two symmetrical lines observed with no quadrupolar-split satellites, that are assigned to the potassium tetrahedral- and octahedral-sites, are found to show the same temperature (T) dependence as the ¹³C-NMR shifts. From roughly estimated spin-lattice relaxation time, it is found that the conduction-electron density at the potassium site is nearly the same as that at the carbon site. These confirm that the uniform Pauli spin susceptibility, whose T dependence is considered to come from the predicted band effect, causes the reductions of both the ¹³C- and ³⁹K-NMR shifts with decreasing T. Two experimental facts are pointed out for the T′ site observed.