Krüger R, Schulz B, Naler S, Rauer R, Budelmann D, Bäckström J, Kim K H, Cheong S-W, Perebeinos V, Rübhausen M
Institut für Angewandte Physik, Universität Hamburg, Jungiusstrasse 9, D-20355 Hamburg, Germany.
Phys Rev Lett. 2004 Mar 5;92(9):097203. doi: 10.1103/PhysRevLett.92.097203. Epub 2004 Mar 3.
Orbital ordering leads to an unconventional excitation spectrum that we investigate by resonance Raman scattering using incident photon energies between 1.7 and 5.0 eV. We use spectral ellipsometry to determine the corresponding dielectric function. Our results show resonant behavior of the phonon Raman cross section when the laser frequency is close to the orbiton-excitation energy of 2 eV in LaMnO3. We show an excellent agreement between theoretical calculations based on the Franck-Condon mechanism activating multiphonon Raman scattering in first order of the electron-phonon coupling and the experimental data of phonons with different symmetries.
轨道有序导致了一种非常规的激发光谱，我们通过使用能量在1.7至5.0电子伏特之间的入射光子进行共振拉曼散射来对其进行研究。我们使用光谱椭偏仪来确定相应的介电函数。我们的结果表明，在LaMnO₃中，当激光频率接近2电子伏特的轨道子激发能量时，声子拉曼截面呈现出共振行为。我们展示了基于弗兰克 - 康登机制在电子 - 声子耦合一阶下激活多声子拉曼散射的理论计算与具有不同对称性的声子的实验数据之间的极佳一致性。
