Detailed inelastic neutron scattering studies on the low-carrier heavy-elec
tron system Yb4As3 and the semi-conducting mixed compound Yb-4(AS(0.6)P(0.4
))(3) reveal that the charge ordering phenomenon, which leads to one-dimens
ional properties, is common to both compounds. No definite magnetic respons
e other than the one-dimensional spin excitations was observed from the pur
e material Yb4As3, which exhibits a heavy-electron anomaly in its transport
properties, for energy transfers above about 0.3 meV. (C) 1999 Elsevier Sc
ience B.V. All rights reserved.