Orbiton-mediated multi-phonon scattering in La$_{1-x}$Sr$_x$MnO$_3$
  We report on Raman scattering measurements of single crystalline La$_{1-x}$Sr$_x$MnO$_3$ ($x$=0, 0.06, 0.09 and 0.125), focusing on the high frequency regime. We observe multi-phonon scattering processes up to fourth-order which show distinct features: (i) anomalies in peak energy and its relative intensity and (ii) a pronounced temperature-, polarization-, and doping-dependence. These features suggest a mixed orbiton-phonon nature of the observed multi-phonon Raman spectra. 
K.-Y. Choi, P. Lemmens, G. G\"untherodt, Yu. G. Pashkevich, V. P.   Gnezdilov, P. Reutler, L. Pinsard-Gaudart, B. B\"uchner,...