Jahn-Teller effect and doping in manganites

摘要

Basic properties of manganites to large extent are determined by cooperative Jahn-Teller effects and Hund's rule coupling. The insulating (undoped) as well as metallic ferromagnetic states can be described from a unified point of view based on implications of these effects and the use of the two-band picture originated from the double degeneracy of the Mn{sup}(3+) ions. At bole doping the system is intrinsically inhomogeneous and the metal-insulator transition should be treated by means of percolation theory. We also discuss evolution of the Jahn-Teller distortions and electronic properties with doping.