Epitaxial strain is a powerful tool to induce functional properties such as ferroelectricity in thin films of materials that do not possess ferroelectricity in bulk form. In this work, a ferroelectric state was stabilized in thin films of the incipient ferroelectric, CaTiO3, through the careful control of the biaxial strain state and TiO6 octahedral rotations. Detailed structural characterization was carried out by synchrotron x-ray diffraction and scanning transmission electron microscopy. CaTiO3 films grown on La0.18Sr0.82Al0.59Ta0.41O3 (LSAT) and NdGaO3 (NGO) substrates experienced a 1.1% biaxial strain state but differed in their octahedral tilt structures. A suppression of the out-of-plane rotations of the TiO6 octahedral in films grown on LSAT substrates resulted in a robust ferroelectric 14 mm phase with remnant polarization ~5 µC/cm2 at 10K and Tc near 140 K. In contrast, films grown on NGO substrates with significant octahedral tilting showed reduced polarization and Tc. These results highlight the key role played by symmetry in controlling the ferroelectric properties of perovskite oxide thin films.
M. D. Biegalski et al., "Impact of Symmetry on the Ferroelectric Properties of CaTiO₃ Thin Films," Applied Physics Letters, vol. 106, no. 16, American Institute of Physics (AIP), Apr 2015.
The definitive version is available at https://doi.org/10.1063/1.4918805
Mechanical and Aerospace Engineering
Keywords and Phrases
Ferroelectricity; Films; Oxide films; Polarization; Scanning electron microscopy; Thin films; Transmission electron microscopy; X ray diffraction, Ferroelectric property; Functional properties; Out-of-plane rotation; Perovskite oxide thin films; Remnant polarizations; Scanning transmission electron microscopy; Structural characterization; Synchrotron x ray diffraction, Ferroelectric films
International Standard Serial Number (ISSN)
Article - Journal
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