title: Anomalous multi-order Raman scattering in LaMnO3: a signature of quantum lattice effects in a Jahn-Teller crystal.
abstract: The multi-order Raman scattering is studied up to fourth order for a detwinned LaMnO3 crystal. Based on a comprehensive data analysis of the polarization-dependent Raman spectra, we show that the anomalous features in the multi-order scattering could be the sidebands on the low-energy mode at about 25 cm(-1). We suggest that this low-energy mode stems from the tunneling transition between the potential energy minima arising near the Jahn-Teller Mn(3+) ion due to the lattice anharmonicity and that the multi-order scattering is activated by this low-energy electronic motion. The sidebands are dominated by the oxygen contribution to the phonon density-of-states, however, there is an admixture of an additional component, which may arise from coupling between the low-energy electronic motion and the vibrational modes.
authors.affiliation: Lebedev Institute of Physics, Russian Academy of Sciences, Moscow, Leninsky Prospekt 53, 119991, Russia. nkovaleva@sci.lebedev.ru
authors.forename: N N
authors.initials: NN
authors.lastname: Kovaleva
authors.forename: O E
authors.initials: OE
authors.lastname: Kusmartseva
authors.forename: K I
authors.initials: KI
authors.lastname: Kugel
authors.forename: A A
authors.initials: AA
authors.lastname: Maksimov
authors.forename: D
authors.initials: D
authors.lastname: Nuzhnyy
authors.forename: A M
authors.initials: AM
authors.lastname: Balbashov
authors.forename: E I
authors.initials: EI
authors.lastname: Demikhov
authors.forename: A
authors.initials: A
authors.lastname: Dejneka
authors.forename: V A
authors.initials: VA
authors.lastname: Trepakov
authors.forename: F V
authors.initials: FV
authors.lastname: Kusmartsev
authors.forename: A M
authors.initials: AM
authors.lastname: Stoneham