VALENCE AND METAL-INSULATOR TRANSITIONS IN THE SPINLESS FALICOV–KIMBALL MODEL INDUCED BY DOPING

Abstract

The influence of doping on valence and metal-insulator transitions in the spinless Falicov–Kimball model is studied by the well-controlled numerical method. Two types of doping are examined, and namely, the substitution of rare-earth ions by non-magnetic ions that introduce (i) one or (ii) no additional electron (per non-magnetic ion) into the conduction band. It is found that the first type of substitution increases the average f-state occupancy of rare-earth ions, whereas the second type of substitution has the opposite effect. In both cases valence changes are accompanied by a doping induced insulator-metal transition. The results obtained are used to describe valence and metal-insulator transitions in the samarium hexaboride solid solutions.