Terahertz ferroelectric soft mode in weakly doped SrTiO.sub.3./sub.: M thin films (M=Mn, Ni, Fe, Co)

0585184 - FZÚ 2025 RIV NL eng J - Článek v odborném periodiku
Zhukova, E.S. - Nekrasov, B.M. - Tyunina, Marina - Vetokhina, Volha - Kocourek, Tomáš - de Prado, Esther - Stolyarov, V.S. - Frolov, A.S. - Melentev, A.V. - Savinov, Maxim - Bush, A.A. - Kozlov, V.I. - Talanov, M. - Gorshunov, B.P.
Terahertz ferroelectric soft mode in weakly doped SrTiO₃: M thin films (M=Mn, Ni, Fe, Co).
Journal of Alloys and Compounds. Roč. 976, Mar (2024), č. článku 173255. ISSN 0925-8388. E-ISSN 1873-4669
Grant CEP: GA ČR(CZ) GA22-10832S; GA MŠMT(CZ) EF16_019/0000760
Grant ostatní: OP VVV - SOLID21(XE) CZ.02.1.01/0.0/0.0/16_019/0000760; AV ČR(CZ) StrategieAV21/26
Program: StrategieAV
Institucionální podpora: RVO:68378271
Klíčová slova: Strontium titanate * thin films * soft mode * terahertz spectroscopy
Obor OECD: Condensed matter physics (including formerly solid state physics, supercond.)
Impakt faktor: 6.2, rok: 2022

Study of terahertz soft-mode in SrTiO3:M thin (150nm) films doped (2 at%) with transition metals M=Mn, Fe, Ni, Co is performed at freq. 7–1000 cm-1 and temper. 5–300 K. The soft mode dielectric strength and frequency follow the Barrett-like temperature behaviours with unusually high quantum temperatures and large in agnitude negative Curie temperatures, indicating strong destabilization of the ferroelectric state due to a combined effect of quantum fluctuations, dead layers at the boundaries of crystallites, misfit strains within crystallites and disorder induced by doping. Dopant-dependent variation in the asymmetry of the Fano resonance describing coupling of the TO2 phonon and continuum states of polarization fluctuations is observed suggesting presence of polar nanoregions in the films. Correlation between asymmetry parameter and Barrett quantum temperature is observed that highlights the complex character of the local structure-dielectric properties relationships in the films.
Trvalý link: https://hdl.handle.net/11104/0352931