Introduction

Abstract

In last decades main attention of experimental and theoretical studies for metallic systems has shifted to the field of transition and rare-earth elements with partially filled 3d-, 4f-, and 5f-electronic shells and based on them chemical compounds. At the beginning of this process in 1960s, the most intriguing phenomenon in this field was metal–insulator phase transition (MI) observed for many transition metal oxides with variations in pressure, temperature, or doping. A decade later a new class of rare-earth compounds was discovered where charge carriers have effective mass value tens and hundreds time larger than free electron mass – so called “heavy fermion” (HF) systems. In such systems a great variety of interesting phenomena were found: phase transitions between magnetic order and superconductivity, appearance and disappearance of local magnetic moments, transport properties anomalies.