Contribution of the Multiplicity Fluctuation in the Temperature Dependence of Phonon Spectra of Rare-Earth Cobaltites
We have studied, both experimentally and theoretically, the unusual temperature dependence of the phonon spectra in NdCoO<sub>3</sub>, SmCoO<sub>3</sub> and GdCoO<sub>3</sub>, where the Co<sup>3+</sup> ion is in the low-spin (LS) ground state, and at t...
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MDPI AG
2020-09-01
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| author | Yuri S. Orlov Alexey E. Sokolov Vyacheslav A. Dudnikov Karina V. Shulga Mikhail N. Volochaev Sergey M. Zharkov Nikolay P. Shestakov Maxim A. Vysotin Sergei G. Ovchinnikov |
| author_facet | Yuri S. Orlov Alexey E. Sokolov Vyacheslav A. Dudnikov Karina V. Shulga Mikhail N. Volochaev Sergey M. Zharkov Nikolay P. Shestakov Maxim A. Vysotin Sergei G. Ovchinnikov |
| author_sort | Yuri S. Orlov |
| collection | DOAJ |
| description | We have studied, both experimentally and theoretically, the unusual temperature dependence of the phonon spectra in NdCoO<sub>3</sub>, SmCoO<sub>3</sub> and GdCoO<sub>3</sub>, where the Co<sup>3+</sup> ion is in the low-spin (LS) ground state, and at the finite temperature, the high-spin (HS) term has a nonzero concentration <inline-formula><math display="inline"><semantics><mrow><msub><mi>n</mi><mrow><mi>H</mi><mi>S</mi></mrow></msub></mrow></semantics></math></inline-formula> due to multiplicity fluctuations. We measured the absorption spectra in polycrystalline and nanostructured samples in the temperature range 3–550 K and found a quite strong breathing mode softening that cannot be explained by standard lattice anharmonicity. We showed that the anharmonicity in the electron–phonon interaction is responsible for this red shift proportional to the <inline-formula><math display="inline"><semantics><mrow><msub><mi>n</mi><mrow><mi>H</mi><mi>S</mi></mrow></msub></mrow></semantics></math></inline-formula> concentration. |
| first_indexed | 2024-03-10T16:11:21Z |
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| institution | Directory Open Access Journal |
| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-03-10T16:11:21Z |
| publishDate | 2020-09-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Molecules |
| spelling | doaj.art-1b13f504a6b140339349ae9e8c1e4f9e2023-11-20T14:26:09ZengMDPI AGMolecules1420-30492020-09-012518431610.3390/molecules25184316Contribution of the Multiplicity Fluctuation in the Temperature Dependence of Phonon Spectra of Rare-Earth CobaltitesYuri S. Orlov0Alexey E. Sokolov1Vyacheslav A. Dudnikov2Karina V. Shulga3Mikhail N. Volochaev4Sergey M. Zharkov5Nikolay P. Shestakov6Maxim A. Vysotin7Sergei G. Ovchinnikov8Kirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, RussiaKirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, RussiaKirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, RussiaInstitute of Engineering Physics and Radio Electronics, Siberian Federal University, 660041 Krasnoyarsk, RussiaKirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, RussiaKirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, RussiaKirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, RussiaKirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, RussiaKirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, RussiaWe have studied, both experimentally and theoretically, the unusual temperature dependence of the phonon spectra in NdCoO<sub>3</sub>, SmCoO<sub>3</sub> and GdCoO<sub>3</sub>, where the Co<sup>3+</sup> ion is in the low-spin (LS) ground state, and at the finite temperature, the high-spin (HS) term has a nonzero concentration <inline-formula><math display="inline"><semantics><mrow><msub><mi>n</mi><mrow><mi>H</mi><mi>S</mi></mrow></msub></mrow></semantics></math></inline-formula> due to multiplicity fluctuations. We measured the absorption spectra in polycrystalline and nanostructured samples in the temperature range 3–550 K and found a quite strong breathing mode softening that cannot be explained by standard lattice anharmonicity. We showed that the anharmonicity in the electron–phonon interaction is responsible for this red shift proportional to the <inline-formula><math display="inline"><semantics><mrow><msub><mi>n</mi><mrow><mi>H</mi><mi>S</mi></mrow></msub></mrow></semantics></math></inline-formula> concentration.https://www.mdpi.com/1420-3049/25/18/4316rare-earth cobalt oxidesmultiplicity fluctuationsphonon spectra |
| spellingShingle | Yuri S. Orlov Alexey E. Sokolov Vyacheslav A. Dudnikov Karina V. Shulga Mikhail N. Volochaev Sergey M. Zharkov Nikolay P. Shestakov Maxim A. Vysotin Sergei G. Ovchinnikov Contribution of the Multiplicity Fluctuation in the Temperature Dependence of Phonon Spectra of Rare-Earth Cobaltites Molecules rare-earth cobalt oxides multiplicity fluctuations phonon spectra |
| title | Contribution of the Multiplicity Fluctuation in the Temperature Dependence of Phonon Spectra of Rare-Earth Cobaltites |
| title_full | Contribution of the Multiplicity Fluctuation in the Temperature Dependence of Phonon Spectra of Rare-Earth Cobaltites |
| title_fullStr | Contribution of the Multiplicity Fluctuation in the Temperature Dependence of Phonon Spectra of Rare-Earth Cobaltites |
| title_full_unstemmed | Contribution of the Multiplicity Fluctuation in the Temperature Dependence of Phonon Spectra of Rare-Earth Cobaltites |
| title_short | Contribution of the Multiplicity Fluctuation in the Temperature Dependence of Phonon Spectra of Rare-Earth Cobaltites |
| title_sort | contribution of the multiplicity fluctuation in the temperature dependence of phonon spectra of rare earth cobaltites |
| topic | rare-earth cobalt oxides multiplicity fluctuations phonon spectra |
| url | https://www.mdpi.com/1420-3049/25/18/4316 |
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