Ultrasonic study of the charge mismatch effect in charge-ordered (Nd0.75Na0.25)x( Nd0.5Ca0.5)(1-x) MnO3

作者：Jiang, Liang; Su, Jinrui; Kong, Hui; Liu, Yi; Zheng, Shiyuan; Zhu, Changfei^*

来源：Journal of Physics: Condensed Matter , 2006, 18(37): 8563-8571.

DOI：10.1088/0953-8984/18/37/014

• MAGNETORESISTANCE
• PHASE
• TEMPERATURE
• TRANSPORT
• MAGNETISM
• SR

The resistivity, magnetization and ultrasonic properties of charge-ordered polycrystalline (Nd0.75Na0.25) x (Nd0.5Ca0.5)(1-x)MnO3 have been investigated from 50 to 300 K. A considerable velocity softening accompanied by an attenuation peak was observed around the charge-ordering transition temperature (T-CO) upon cooling. The simultaneous occurrence of the charge ordering (CO) and the ultrasonic anomaly implies strong electron-phonon coupling, which originates from the cooperative Jahn-Teller effect. At very low temperature, another broad attenuation peak was observed, which is attributed to the phase separation (PS) and gives a direct evidence of spin-phonon coupling in the compound. With increasing x, T-CO shifts to lower temperature, the magnetization of the system is strengthened and the PS is enhanced. The temperature dependence of the longitudinal modulus shows that the Jahn-Teller coupling energy E-JT decreases with increasing Na content. The analysis suggests that the charge mismatch effect may be the main reason for the suppression of the CO and enhancement of the PS.

• 出版日期2006-9-20
• 单位中国科学技术大学