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Pis'ma v Zhurnal Èksperimental'noi i Teoreticheskoi Fiziki, 2010, Volume 91, Issue 7, Pages 363–368
(Mi jetpl683)
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This article is cited in 7 scientific papers (total in 7 papers)
CONDENSED MATTER
Nature of the low-energy excitations of a charge-ordered phase of La0.25Ca0.75MnO3 manganites
B. P. Gorshunova, E. S. Zhukovaa, E. G. Maksimovb, A. S. Prokhorova, V. I. Torgashevc, T. Zhangde, D. Wue, M. Dressele a General Physics Institute named after A. M. Prokhorov, Russian Academy of Sciences
b P. N. Lebedev Physical Institute, Russian Academy of Sciences
c Southern Federal University, Physics Department
d Institute of Solid State Physics, Chinese Academy of Sciences
e Physikalisches Institut, Universität Stuttgart
Abstract:
The nature of the low-energy excitations of polycrystalline and nanostructured La0.25Ca0.75MnO3 samples has been analyzed in order to investigate the mechanisms of charge ordering in manganites. It has been found that the electrodynamic response spectra of La0.25Ca0.75MnO3 in the energy range of 0.5 to 90 meV and the temperature range of 5 to 300 K have no resonance features that could be attributed to the collective excitations of the charge-ordered phase. It has been shown that the absorption lines observed at frequencies of 20–40 and 80–100 cm–1 are attributed to usual acoustic phonons becoming optically active owing to the structure phase transition and the appearance of a fourfold superstructure with a quadruple period along the crystallographic a axis. The suppression of the superstructure has been revealed in samples with nanocrystallites (≤40 nm). This suppression indicates a relatively weak coupling of the charge and magnetic order parameters with the phonon subsystem.
Received: 15.02.2010
Citation:
B. P. Gorshunov, E. S. Zhukova, E. G. Maksimov, A. S. Prokhorov, V. I. Torgashev, T. Zhang, D. Wu, M. Dressel, “Nature of the low-energy excitations of a charge-ordered phase of La0.25Ca0.75MnO3 manganites”, Pis'ma v Zh. Èksper. Teoret. Fiz., 91:7 (2010), 363–368; JETP Letters, 91:7 (2010), 336–340
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