THE EFFECT OF CO-DOPING ON ANTIFERROMAGNETIC CORRELATIONS IN THE KONDO SEMIMETAL CENISN

Single-crystal neutron scattering experiments have been performed to s tudy magnetic excitations in CeNi0.9Co0.1Sn, in which the pseudo-gap o f CeNiSn is suppressed by the doping. In CeNiSn there are two inelasti c excitation peaks at <(h)over bar omega> = 2 and 4 meV, which corresp ond to dynamic antiferromagnetic correlations. In CeNi0.9Co0.1Sn the 2 meV peak is smeared out, whereas the 4 meV peak becomes very weak and broad, but preserves the same quasi-one-dimensional character as that for CeNiSn. These results suggest the strong relation between the ant iferromagnetic correlations and the pseudo-gap formation.