One-dimensional antiferromagnetic coupling in the low-carrier heavy-electron systemYb4As3:The role of charge ordering

Inelastic-neutron-scattering experiments on ${\mathrm{Yb}}_4{\mathrm{As}}_3$ revealed the existence of low-energy spin excitations, which are characteristic of a one-dimensional Heisenberg-type antiferromagnetic coupling at low temperatures where charge ordering takes place. Superimposed on the one-dimensional spin excitations, an unusual magnetic response is also observed around the one-dimensional zone center. These results strongly suggest that the heavy-electron behavior in ${\mathrm{Yb}}_4{\mathrm{As}}_3$ is a unique phenomenon caused by charge ordering; it results from the fact that the compound contains doped one-dimensional ${4f}^1$ hole chains with strong on-site $f$-electron correlations.