Temperature and electric field tuning of the ferroelectric soft modein a strained SrTiO.sub.3./sub. / DyScO.sub.3./sub. heterostructure

0343463 - FZÚ 2011 RIV US eng J - Journal Article
Kadlec, Christelle - Skoromets, Volodymyr - Kadlec, Filip - Němec, Hynek - Hlinka, Jiří - Schubert, J. - Panaitov, G. - Kužel, Petr
Temperature and electric field tuning of the ferroelectric soft modein a strained SrTiO₃ / DyScO₃ heterostructure.
Physical Review. B. Roč. 80, č. 17 (2009), 174116/1-174116/6. ISSN 1098-0121
R&D Projects: GA AV ČR(CZ) IAA100100907; GA MŠMT LC512
Institutional research plan: CEZ:AV0Z10100520
Keywords : strontium titanate * terahertz * strained films * ferroelectrics
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 3.475, year: 2009

We studied THz dielectric spectra of SrTiO3/DyScO3 epitaxial multilayers with four 50-nm-thick layers of each compound deposited on DyScO3 substrate as a function of temperature and electric field. At room temperature, SrTiO3 is in the paraelectric phase and the soft-mode frequency is shifted down to 47 cm-1. The ferroelectric phase transition occurs in the strained SrTiO3 layers around 270 K and in the ferroelectric phase the soft-mode hardening upon temperature decrease is observed. The soft mode is linearly coupled to an excitation of relaxation type at 10 cm-1 at all temperatures. This relaxation is silent in the paraelectric phase, but it becomes coupled to the polarization below the ferroelectric transition temperature. The recently proposed universal model of soft-mode behavior in strained SrTiO3 films [C. Kadlec et al., J. Phys.: Condens. Matter 21, 115902 (2009)] was generalized to describe the observed spectra at all temperatures and applied fields.
Permanent Link: http://hdl.handle.net/11104/0185939