Charge and spin ordering in perovskite manganites

A magnetic phase diagram of the ground state of perovskite manganites is studied in a mean field approximation by putting emphasis on the coupling of charge and spin degrees of freedom. It is shown that a characteristic feature of the ground state observed near the quarter-filling can be reproduced, that is, the charge ordered state with a spin spiral ordering appears, being nearly degenerate with the fully polarized ferromagnetic state. Coupling of orbital and charge degrees of freedom and the electronic phase separation are also examined. (C) 2000 Elsevier Science Ltd. All rights reserved.