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Ultrasonic Study on Charge Ordering in Nd0.5Ca0.5Mn1-xAlxO3 (x=0,0.03)
Yi Liu ,Hui Kong ,Jin-rui Su ,Chang-fei Zhu*
Author NameAffiliation
Yi Liu Laboratory of Advanced Functional Materials and Devices, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China 
Hui Kong Laboratory of Advanced Functional Materials and Devices, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China 
Jin-rui Su Laboratory of Advanced Functional Materials and Devices, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China 
Chang-fei Zhu* Laboratory of Advanced Functional Materials and Devices, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China 
Abstract:
The ultrasonic, magnetic and transport properties of Nd0.5Ca0.5Mn1-xAlxO3 (x=0, 0.03) were studied from 15 to 300 K. The temperature dependencies of resistivity and magnetization show that Nd0.5Ca0.5Mn1-xAlxO3 undergoes a charge ordering transition at TCO?257 K. An obvious softening of the longitudinal sound ve- locity above TCO and a dramatic stiffening below TCO accompanied by an attenuation peak were observed. These features imply a strong electron-phonon interaction via the Jahn-Teller effect in the sample. Another broad attenuation peak was observed at around Tp?80 K. This anomaly is attributed to the phase separa- tion between the antiferromagnetic (AFM) and paramagnetic (PM) phases and gives a direct evidence for spin-phonon coupling in the compound. For the x=0.03 sample, both the minimum of sound velocity and attenuation peaks shift to a lower temperature. The results indicate that the charge ordering and CE-type AFM state in Nd0.5Ca0.5Mn1-xAlxO3 are both partially suppressed by replacing Mn with Al.
Key words:  Manganite, Charge ordering, Phase separation, Ultrasonic velocity and attenuation
FundProject:supported by the National Natural Science Foundation of China (No.10274075) and the Specialized Research Fund for the Doctoral Program of Higher Education (No.20030358056)
Nd0.5Ca0.5Mn1-xAlxO3 (x=0,0.03)体系中电荷有序态的超声研究
刘毅 ,孔辉 ,苏金瑞 ,朱长飞
摘要:
系统研究了Nd0:5Ca0:5Mn1-xAlxO3 (x=0,0.03) 单相多晶 样品在低温下的电磁性质和超声特性. 电阻和磁化率测量表 明,Nd0:5Ca0:5O3体系在Tco?257 K处发生了电荷有序相变. 超声 声速从室温开始随着温度的降低逐渐减小,并在Tco附近达到最小, 之后,随着温度的进一步降低,声速急剧增加,同时伴随着一个尖锐 的超声衰减峰出现. Tco附近的超声异常表明体系中存在着强烈的电- 声子相互作用,该电-声子耦合来源于Mn3+的Jahn-Teller 效应. 在低 温下,出现了
关键词:  锰氧化物,电荷有序,相分离,超声声速与衰减
DOI:10.1360/cjcp2006.19(6).535.4
分类号: