METAL-INSULATOR-TRANSITION IN KONDO INSULATORS - A FUNCTIONAL-INTEGRAL APPROACH

We present a theory to describe the metal-insulator transition as a fu nction of pressure and temperature in Kondo insulators. A two-band mod el is introduced and we treat the electronic correlations using a func tional-integral approach in the static approximation. The effects of p ressure and temperature on the electronic structure of the system and the phase diagram are discussed. In particular we find the critical li ne separating the (paramagnetic) insulating from the metallic phase an d the exponents characterizing the vanishing of the gap close to this line. We compare our results with experiments and previous theoretical approaches.