Split of In-plane and Out-of-plane Ferroelectric Instabilities in Compressed (001)-epitaxial SrTiO3 Film

0045431 - ÚJF 2007 US eng A - Abstrakt
Yamada, T. - Petzelt, Jan - Tagantsev, A. - Denisov, Sergey - Noujni, Dmitri - Petrov, P.K. - Macková, Anna - Kiguchi, T. - Fujito, K. - Shinozaki, K. - Mizutani, N. - Sherman, V.O. - Muralt, P. - Setter, N.
Split of In-plane and Out-of-plane Ferroelectric Instabilities in Compressed (001)-epitaxial SrTiO3 Film.
[Rozštěpení feroelektrické nestability ve stlačených epitaxních vrstvách SrTiO3.]
Bok of abstracts. Boston: -, 2006. s. 8.
[Materials Research Society Fall meeting. 27.10.2006-01.12.2006, Boston]
Grant CEP: GA AV ČR KJB100480601
Výzkumný záměr: CEZ:AV0Z10480505
Klíčová slova: ferroelectric instabilities * SrTiO3
Kód oboru RIV: BM - Fyzika pevných látek a magnetismus

It is well recognized that the mechanical coupling between ferroelectric thin films and their substrates can strongly influence the symmetry of the films and their properties. However, it is less recognized that the film-substrate mechanical coupling will lead to the substantially different in-plane and out-of-plane properties of the film, which brings a qualitatively new effect - a split of the in-plane and out-of-plane ferroelectric instability temperatures. We show here the first observation of such a split by means of infrared (IR) reflection spectroscopy in biaxially strained epitaxial STO thin films. High quality epitaxial 50 nm-thick STO (100) film was deposited on NdGaO3(110) substrate by pulsed laser deposition. The film was strongly in-plane compressed and out-of-plane elongated due to the lattice mismatch between film and substrate. IR reflection spectroscopy revealed the very slow softening of the stiffened in-plane soft mode on cooling. At the same time, another feature, a phonon silent mode, was observed in the spectra below 150 K, corresponding to the appearance of an out-of-plane spontaneous polarization in the film.
Trvalý link: http://hdl.handle.net/11104/0137953