Anharmonicity of the antiferrodistortive soft mode in barium zirconate BaZrO.sub.3./sub.

0574090 - FZÚ 2024 RIV US eng J - Článek v odborném periodiku
Rosander, P. - Fransson, E. - Milesi-Brault, Cosme - Toulouse, C. - Bourdarot, F. - Piovano, A. - Bossak, A. - Guennou, M. - Wahnström, G.
Anharmonicity of the antiferrodistortive soft mode in barium zirconate BaZrO₃.
Physical Review B. Roč. 108, č. 1 (2023), č. článku 014309. ISSN 2469-9950. E-ISSN 2469-9969
Grant CEP: GA MŠMT(CZ) EF16_019/0000760
Grant ostatní: OP VVV - SOLID21(XE) CZ.02.1.01/0.0/0.0/16_019/0000760
Institucionální podpora: RVO:68378271
Klíčová slova: perovskites * DFT * inelastic scattering * phonons * ferroelectricity * ferrodistortive
Obor OECD: Condensed matter physics (including formerly solid state physics, supercond.)
Impakt faktor: 3.7, rok: 2022
Způsob publikování: Open access

Barium zirconate (BaZrO3) is one of the very few perovskites that is claimed to retain an average cubic structure down to 0K, while being energetically very close to an antiferrodistortive phase obtained by condensation of a soft phonon mode at the R point of the Brillouin zone boundary. In this work, we report a combined experimental and theoretical study of the temperature dependence of this soft phonon mode. Inelastic neutron and x-ray scattering measurements on single crystals show that it softens substantially from 9.4meV at room temperature to 5.6meV at 2K. In contrast, the acoustic mode at the same R point is nearly temperature independent. The effect of the anharmonicity on the lattice dynamics is investigated nonperturbatively using direct dynamic simulations as well as a first-principles-based self-consistent phonon theory, including quantum fluctuations of the atomic motion.

Trvalý link: https://hdl.handle.net/11104/0344448