/ Yu. S. Orlov [et al.]> // Phys. Rev. B. - 2013. -
Vol. 88,
Is. 23. - Ст. 235105. - P. ,
DOI 10.1103/PhysRevB.88.235105
. - ISSN 1098-0121
Перевод заглавия: Структурные свойства и высокотемпературные спиновые и электронные переходы в GdCoO3: эксперимент и теория
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 Eg=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 TIMT=780 K. Heat-capacity measurements revealed a smooth maximum near the TIMT. © 2013 American Physical Society.
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Держатели документа: Russian Acad Sci, LV Kirensky Inst Phys, Siberian Branch, Krasnoyarsk 660036, Russia
Siberian Fed Univ, Krasnoyarsk 660041, Russia
Russian Acad Sci, Siberian Branch, Inst Chem & Chem Technol, Krasnoyarsk 660049, Russia
Moscow MV Lomonosov State Univ, Fac Phys, Moscow 119991, Russia
Natl Acad Sci Ukraine, OO Galkin Donetsk Inst Phys & Engn, UA-83114 Donetsk, Ukraine
MF Reshetnev Siberian State Aerosp Univ, Krasnoyarsk 660014, Russia;
Доп.точки доступа: Orlov, Yu.S.; Орлов, Юрий Сергеевич; Solovyov, L. A.; Соловьев, Леонид Александрович; Dudnikov, V. A.; Дудников, Вячеслав Анатольевич; Fedorov, A. S.; Федоров, Александр Семенович; Kuzubov, A. A.; Кузубов, Александр Александрович; Kazak, N. V.; Казак, Наталья Валерьевна; Voronov, V. N.;
Воронов,
Владимир Николаевич; Vereshchagin, S. N.; Shishkina, N. N.; Perov, N. S.; Lamonova, K. V.; Babkin, R.Yu.; Pashkevich, Yu.G.; Anshits, A. G.; Аншиц, Александр Георгиевич; Ovchinnikov, S. G.; Овчинников, Сергей Геннадьевич