The properties of the semiconducting phase of heavy-fermion systems are examined within the framework of mean-field theory. The theory exhibits the possibility of a transition from a high-temperature local-moment state to a low-temperature, semiconducting state. The low-temperature, semiconducting state has an indirect band gap that is reduced by many-body renormalizations. The magnetic properties of this system are examined within this mean-field approximation and are compared with the results of recent inelastic-neutron-scattering experiments.

• Received 26 December 1991

DOI:https://doi.org/10.1103/PhysRevB.45.13984