Systematic study of terahertz response of SrTiO.sub.3./sub. based heterostructures: Influence of strain, temperature, and electric field

0434411 - FZÚ 2015 RIV US eng J - Journal Article
Skoromets, Volodymyr - Kadlec, Christelle - Drahokoupil, Jan - Schubert, J. - Hlinka, Jiří - Kužel, Petr
Systematic study of terahertz response of SrTiO₃ based heterostructures: Influence of strain, temperature, and electric field.
Physical Review. B. Roč. 89, č. 21 (2014), , "214116-1"-"214116-12". ISSN 1098-0121
R&D Projects: GA ČR(CZ) GA14-25639S
EU Projects: European Commission(XE) 607521 - NOTEDEV
Institutional support: RVO:68378271
Keywords : dielectric response * terahertz spectroscopy * ferroelectrics * thin films * phase transition
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 3.736, year: 2014
http://journals.aps.org/prb/abstract/10.1103/PhysRevB.89.214116

Epitaxial heterostructures consisting of a variable number of SrTiO3/DyScO3 bilayers deposited on DyScO3 substrates were investigated using time-domain terahertz spectroscopy down to helium temperatures. The phase transition into a ferroelectric state is observed in SrTiO3 films in all samples close to 300 K due to in-plane epitaxial strain induced by the substrate and intercalated layers of DyScO3. Evolution of the dielectric spectra with temperature and external electric field is described by a general model which involves a damped harmonic oscillator (soft mode) coupled to a Debye relaxation (central mode). Both modes are connected with the soft mode eigenvector and they reflect a strong anharmonicity of the soft-mode potential. The observed variation of phase transition temperature and of the dielectric response among the structures is ascribed to a partial epitaxial strain relaxation confirmed also by x-ray diffraction.
Permanent Link: http://hdl.handle.net/11104/0238457