Metal-insulator transition in (Pr, Y).sub.0.7./sub.Ca.sub.0.3./sub.CoO.sub.3./sub. in the far-infrared spectral region

0536507 - FZÚ 2021 RIV US eng J - Journal Article
Němec, Hynek - Kadlec, Christelle - Goian, Veronica - Borodavka, Fedir - Železný, Vladimír - Kempa, Martin - Knížek, Karel - Hejtmánek, Jiří - Buršík, Josef - Soroka, Miroslav
Metal-insulator transition in (Pr, Y)_0.7Ca_0.3CoO₃ in the far-infrared spectral region.
Physical Review B. Roč. 102, č. 19 (2020), s. 1-13, č. článku 195105. ISSN 2469-9950. E-ISSN 2469-9969
R&D Projects: GA MŠMT(CZ) EF16_019/0000760; GA ČR GA17-04412S
Grant - others:OP VVV - SOLID21(XE) CZ.02.1.01/0.0/0.0/16_019/0000760
Institutional support: RVO:68378271 ; RVO:61388980
Keywords : terahertz spectroscopy * mixed-valence cobaltites
OECD category: Condensed matter physics (including formerly solid state physics, supercond.); Inorganic and nuclear chemistry (UACH-T)
Impact factor: 4.036, year: 2020
Method of publishing: Limited access
https://doi.org/10.1103/PhysRevB.102.195105

Bulk ceramics and thick nanogranular films of mixed-valence cobaltite (Pr1−yYy)0.7Ca0.3CoO3 were studied using time-domain THz transmission spectroscopy and infrared reflection spectroscopy. The terahertz conductivity spectrum shows that the transition is not a simple cross-over between two states. As the charges become delocalized during the insulator to metal transition, a broad resonant mode corresponding to the eigenfrequency of the binding potential appears in the terahertz conductivity spectra in the ceramics, and it further softens as the metallic state prevails. This is a consequence of the complexity of charge motion in a temperature-dependent energy landscape, changing from the tightly bound charges on atomic distance in the insulating phase to almost free charges in the metallic phase. The insulator to metal transition is also accompanied by a weak softening of infrared-active phonon modes, which is related to the expansion of lattice parameters upon phase transition.

Permanent Link: http://hdl.handle.net/11104/0314283