Contributions to polarization and polarization switching in antiphase boundaries of SrTiO<sub>3</sub> and PbZrO<sub>3</sub>

W. Schranz, A. Tröster, I. Rychetsky

We use a recently developed method-based on layer group analysis combined with the Landau theory-to investigate the polar properties of antiphase boundaries (APBs) inSrTiO 3 andPbZrO 3. ForSrTiO 3, we find that, in addition to the biquadratic, Houchmandazeh-Laizerowicz-Salje (HLS) couplingbi j k lP iP jphi kphi l in the Landau-Ginzburg free energy expansion, additional rotopolar terms of the formWi j k lP iphi kpartial derivativephi lpartial derivativex j contribute considerably to the polarization of antiphase boundaries in these materials. The rotopolar terms can be split into a symmetric flexoelectric part and an antisymmetric one. The antisymmetric Lifshitz term leads to a macroscopic polarization of APBs, which can be switched by application of an external electric field. ForPbZrO 3, the observed polarization profiles [Wei et al., Mater. Res. Bull. 62, 101 (2015)] are fully compatible with the symmetries of the corresponding layer groups. Unlike inSrTiO 3, there exists no Lifshitz invariantWi j k lP ieta kpartial derivativeeta lpartial derivativex j for the order parametereta i ( i = 1 , ... , 12 ) describing the displacements of lead atoms. However, a detailed group theoretical treatment indicates that the polarity of APBs in PbZrO3 is driven by higher order interactions between polarizationP i, order parametereta k, and order parameter gradientspartial derivativeeta lpartial derivativex j.

Physics of Functional Materials, Computational and Soft Matter Physics
External organisation(s)
Czech Academy of Sciences
Journal of Applied Physics
No. of pages
Publication date
Peer reviewed
Austrian Fields of Science 2012
103018 Materials physics, 103042 Electron microscopy
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