Order-disorder in the Jahn-Teller transition of LaMnO 3 : A Raman scattering study
Order-disorder in the Jahn-Teller transition of LaMnO 3 : A Raman scattering study
复制标题
DOI：
10.1103/physrevb.62.11304
复制
发表时间：
2000-03
影响因子：
3.7
通讯作者：
E. Granado;J. Sanjurjo;C. Rettori;J. Neumeier;S. Oseroff
中科院分区：
文献类型：
--
作者：
E. Granado;J. Sanjurjo;C. Rettori;J. Neumeier;S. Oseroff
用拉曼散射研究了多晶样品{{mathm{LaMnO}}{3}$的高T‘’正交立方‘’Jahn-Teller(JT)相变.以${\mathm{CaMnO}}_{3}$陶瓷样品作为参比化合物。当T从下向下接近JT转变温度时，观察到{{\mathm{LaMnO}}_{3}$拉曼模式显著展宽。声子线宽与T的强烈依赖关系表明，在较低的温度下已经存在相当大的晶格无序。我们的结果表明，在{\mathm{LaMnO}}_{3}$中的JT相变是有序-无序类型的，并且是由${\mathm{mN}}{3+}$离子的热激活轨道无序驱动的。
The high-$T$ ``orthorhombic-cubic'' Jahn-Teller (JT) transition of a polycrystalline sample of ${\mathrm{LaMnO}}_{3}$ is studied by Raman scattering. A ${\mathrm{CaMnO}}_{3}$ ceramic sample is used as a reference compound. Dramatic broadening of the ${\mathrm{LaMnO}}_{3}$ Raman modes are observed as T approaches the JT transition temperature ${(T}_{\mathrm{JT}})$ from below. The strong T dependence of the phonon linewidth suggests that considerable lattice disorder is already present at temperatures well below ${T}_{\mathrm{JT}}.$ Our results indicate that the JT transition in ${\mathrm{LaMnO}}_{3}$ is of order-disorder type and is driven by thermally activated ${e}_{g}$ orbital disorder of the ${\mathrm{Mn}}^{3+}$ ion in the ${\mathrm{MnO}}_{6}$ octahedra.