Giant increase of ferroelectric phase transition temperature in highly strained ferroelectric  superlattice

J. Belhadi; M. El Marssi; Y. Gagou; Yu. I. Yuzyuk; I. P. Raevski

doi:10.1209/0295-5075/106/17004

All issues

Volume 106 / No 1 (April 2014)

EPL, 106 1 (2014) 17004

Abstract

Issue		EPL Volume 106, Number 1, April 2014


Article Number		17004
Number of page(s)		5
Section		Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
DOI		https://doi.org/10.1209/0295-5075/106/17004
Published online		07 April 2014

EPL, 106 (2014) 17004

Giant increase of ferroelectric phase transition temperature in highly strained ferroelectric $[{\text{BaTiO}}_{3}]_{0.7\Lambda}/[{\text{BaZrO}}_{3}]_{0.3\Lambda}$ superlattice

J. Belhadi¹, M. El Marssi¹^(a), Y. Gagou¹, Yu. I. Yuzyuk² and I. P. Raevski²

¹ Laboratoire de Physique de la Matière Condensée, Université de Picardie - 33 rue Saint-Leu, 80039 Amiens Cedex, France
² Faculty of Physics, Southern Federal University - 5, Zorge str. Rostov-on-Don, 344090, Russia

^(a) mimoun.elmarssi@u-picardie.fr (corresponding author)

Received: 18 March 2014
Accepted: 24 March 2014

Abstract

We report epitaxial strain effects in the lead-free ferroelectric/paraelectric superlattice (SL) $[{\text{BaTiO}}_{3}]_{0.7\Lambda}/[{\text{BaZrO}}_{3}]_{0.3\Lambda}$ for a modulation period Λ of about 100 Å. We have demonstrated that the large strain in SL induces ferroelectricity in BaZrO₃ layers, a material that is paraelectric at any temperature in the bulk form. The induced polar axis in BaZrO₃ layers is perpendicular to the plane of the substrate while BaTiO3 layers exhibit in-plane polar orientation. Raman spectroscopy revealed a lattice ordering in SL due to the misfit strain generated by the large lattice mismatch between the alternating BaZrO₃ and BaTiO₃ layers. Such strain induces a huge upward frequency shift of the lowest E(1TO) soft mode from $60\ \text{cm}^{-1}$ in the BaTiO₃ single film to $207\ \text{cm}^{-1}$ in the SL. The temperature of the ferroelectric phase transition in the SL was found to be upshifted by about $300\ ^{\circ}\text{C}$ with respect to the BaTiO₃ single crystal.

PACS: 77.55.fe – BaTiO3-based films / 78.30.-j – Infrared and Raman spectra

© EPLA, 2014

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