Volume 86, Number 5, June 2009
|Number of page(s)||5|
|Section||Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics|
|Published online||09 June 2009|
Variation of ultrasonic behaviors in R1/3Sr2/3FeO3 (R = La, Pr, Gd)
Laboratory of Advanced Functional Materials and Devices, Department of Materials Science and Engineering, University of Science and Technology of China - Hefei, Anhui, 230026, PRC
2 School of Metallurgy and Resources, Anhui University of Technology - Maanshan, Anhui, 243002, PRC
Corresponding author: email@example.com
Accepted: 7 May 2009
The longitudinal ultrasonic velocity (V), as well as resistivity and magnetization has been measured in polycrystalline R1/3Sr2/3FeO3 (R = La, Pr, Gd). When the R-site ion is changed from La to smaller-size R ion, the charge ordering (CO) transition shifts to lower temperature and finally disappears for R = Gd. Dramatic anomalies in V for the R = La, Pr compounds are observed near the CO transition temperature, which implies the electron-phonon coupling arising from the Jahn-Teller effect of Fe4+. And the theory calculation result shows that this coupling is weakened for Pr, which may lead to the shift of . In the case of Gd1/3Sr2/3FeO3 with no CO transition, the anomaly in V is small, and may be attributed to the antiferromagnetic spin fluctuations. Below , another unexpected softening in V is discerned in La1/3Sr2/3FeO3, while only a slope change is observed in Pr1/3Sr2/3FeO3. This feature is attributed to the breathing-type distortion of Fe-O octahedron via the charge disproportionation, which is weakened in Pr1/3Sr2/3FeO3.
PACS: 43.35.+d – Ultrasonics, quantum acoustics, and physical effects of sound / 64.70.K- – Solid-solid transitions / 71.38.-k – Polarons and electron-phonon interactions
© EPLA, 2009
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