Abstract
The role of the cooperative Jahn-Teller effect in the charge-ordered La 1-x Ca x MnO 3 manganites was discussed. It was found that with increasing the fraction of Q 3 mode of JT distortion and decreasing that of Q 2 mode in the CO state, the mangetic structure evolved from charge-exchange-type to C-type. It was found that the stability of CO state and the cooperative JT lattice distortion increased. Analysis show that the cooperative JT effect with different vibration modes was the key ingredient in understanding the essential physics of the CO state.