A magnetic phase diagram of the ground state of layered perovskite manganites is studied in a mean-field approximation for a two-orbital double exchange model with the superexchange interaction between localized spins and Jahn-Teller effect. We take into account the G-type and C-type spin alignment and their canted spin ordering. It is shown that with increasing electron dopant the ground state changes from the G-type state to ferromagnetic state via a G-type canted spin state. The C-type state appears only for the intermediate electron dopant with stronger superexchange interaction. The Jahn-Teller distortion stabilizes 3y2-r2 orbital ordering in the C-type state while x2-y2 ordering occurs in other cases. It is also shown that rather complex electronic phase separation occurs, which is compared with experimental observations.
Physical Review B
- Pub Date:
- April 2002
- Exchange and superexchange interactions;
- Spin arrangements in magnetically ordered materials;
- Non-Fermi-liquid ground states electron phase diagrams and phase transitions in model systems