TEMPERATURE-DRIVEN METAL-NON-METAL TRANSITION IN KONDO INSULATORS

We present a theory to describe the metal-insulator transition as a fu nction of pressure and temperature in Kondo insulators. We use a two-b and model and treat the electronic correlations via a functional integ ral approach in the static approximation. The effects of pressure and temperature on the electronic structure of the system and the phase di agram are discussed. We obtain the critical line and the exponents cha racterizing the vanishing of the gap close to this line and compare ou r results with those obtained using a periodic Anderson lattice model (PAM). (C) 1998 Elsevier Science B.V. All rights reserved.