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Structural properties and high-temperature spin and electronic transitions in GdCoO3: Experiment and theoryстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 4 февраля 2014 г.
- Авторы: Orlov Yu S., Solovyov L.A., Dudnikov V.A., Fedorov A.S., Kuzubov A.A., Kazak N.V., Voronov V.N., Vereshchagin S.N., Shishkina N.N., Perov N.S., Lamonova K.V., Babkin R.Yu, Pashkevich Yu G., Anshits A.G., Ovchinnikov S.G.
- Журнал: Physical Review B
- Том: 88
- Номер: 23
- Год издания: 2013
- Издательство: American Physical Society
- Местоположение издательства: United States
- Первая страница: 235105
- Последняя страница: 235105
- DOI: 10.1103/PhysRevB.88.235105
- Аннотация: We have investigated the x-ray diffraction (XRD) structure, magnetic susceptibility, and heat capacity of GdCoO3 in a wide temperature range. A model of phase separation of the low-spin (LS) and high-spin (HS) states has been proposed based on the analysis of XRD peak shape anomalies in the temperature range 200-800 K. From magnetic measurements we separated the HS Co3+ contribution and fitted it with the temperature-dependent spin gap. We found a smooth LS-HS crossover at T = 800 K. The possible contribution of the intermediate spin (IS) state to the thermodynamics is excluded by the calculation IS-LS excitation energy within the modified crystal-field approach. In the two-phase model, with HS/LS probabilities calculated from the found spin gap and the LS and HS volumes calculated by the DFT-GGA method, we were able to reproduce the temperature dependence of the unit-cell volume and thermal expansion. Thus, we conclude that in GdCoO3 the main mechanism of the lattice expansion is not the conventional lattice anharmonicity, but the HS/LS fluctuations. The electronic structure has been calculated by the LDA+GTB method. At zero temperature, we have obtained the charge-transfer insulator with the charge gap E-g = 0.5 eV. The thermal population of the HS term results in the in-gap band formation inside the insulator gap and smooth insulator-metal transition at T-IMT = 780 K. Heat-capacity measurements revealed a smooth maximum near the T-IMT.
- Добавил в систему: Перов Николай Сергеевич