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Anomalous multi-order Raman scattering in LaMnO3: a signature of quantum lattice effects in a Jahn-Teller crystal
journal contributionposted on 2014-11-30, 11:24 authored by Natalia Kovaleva, Olga Kusmartseva, K.I. Kugel, A.A. Maksimov, D. Nuzhnyy, A.M. Balbashov, E.I. Demikhov, A. Dejneka, V.A. Trepakov, Feodor Kusmartsev, Arthur Marshall Stoneham
The multi-order Raman scattering is studied up to a fourth order for a detwinned LaMnO3 crystal. Based on a comprehensive data analysis of the polarisation-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 Mn3+ ion due to the lattice anharmonicity, and 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. We suggest that superexchange interaction may be crucial in driving the system to the regime of the dynamic Jahn-Teller effect, with affordable barriers for the tunneling between the potential energy minima.
This work was supported by the ESF network-program AQDJJ, the Royal Society of London (grant JP 090710), the Russian Foundation for Basic Research (projects10- 02-92600-KO and 11-02-00708), Program of the Presidium RAS “Quantum mesoscopic and disordered systems”, grant TA01010517 of the TACR (Technology Agency of the Czech Republic), and AV0Z10100522 of the ASCR (Academy of Sciences of the Czech Republic).
Published inJOURNAL OF PHYSICS-CONDENSED MATTER
Pages? - ? (8)
CitationKOVALEVA, N.N. ... [et al.], 2013. Anomalous multi-order Raman scattering in LaMnO3: a signature of quantum lattice effects in a Jahn-Teller crystal. Journal of Physics: Condensed Matter, 25 (15), no. 155602.
- AM (Accepted Manuscript)
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