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要旨

We report measurements of the elastic and inelastic neutron scattering, initial susceptibility and high-field magnetization on thoroughly prepared poly- and single crystalline samples of CeB6. Part of these experiments have been performed at temperatures down to 60 mK and magnetic fields up to 70 kØe. Our neutron-diffraction data provide the first proof that CeB6 is an antiferromagnet belowT N≃2K as has been suggested by previous bulk experiments. The reduced value of the low-temperature magnetic moment both below and aboveT N points to the existence of a Kondo effect of theΓ 7 crystal-field (CF) ground state of Ce3+. From the low-temperature width of the quasielastic neutron line, the Kondo temperature is inferred to beT K≃3 K. The thermal variation of the initial susceptibility (forT>20K) is semiquantitatively explained invoking, besides the Kondo effect, aΓ 7-Γ 8 CF splitting of ≃70 K and magnetic interactions, which are about 10 times stronger betweenΓ 8 states than those betweenΓ 7 states. This largeΓ 8-Γ 8 exchange interaction is also assumed to account for the most striking result of this work, i.e. the lack of any CF-transition peak up to 44 meV in our inelastic neutron-scattering spectra.