Interplay of epitaxial strain and rotations in PbTiO${}_3$/PbZrO${}_3$ superlattices from first principles

Abstract

We present first-principles calculations of the structural phase behavior of the [1:1] \pzta\ superlattice and the \ptoa\ and \pzoa\ parent compounds as a function of in-plane epitaxial strain. A symmetry analysis is used to identify the phases and clarify how they arise from an interplay between different kinds of structural distortions, including out-of-plane and in-plane polar modes, rotation of oxygen octahedra around out-of-plane or in-plane axes, and an anti-polar mode. Symmetry-allowed intermode couplings are identified and used to elucidate the nature of the observed phase transitions. For the minimum-period [1:1] \pzta\ superlattice, we identify a sequence of three transitions that occur as the in-plane lattice constant is increased. All four of the phases involve substantial oxygen octahedral rotations, and an antipolar distortion is important in the high-tensile-strain phase. Inclusion of these distortions is found to be crucial for an accurate determination of the phase boundaries.

8 pages, 4 figures

References in corpus (3)

• Structure and properties of functional oxide thin films: Insights from electronic-structure calculations
• Pressure-Induced Anomalous Phase Transitions and Colossal Enhancement of Piezoelectricity in PbTiO${}_3$
• Phase diagram of Pb(Zr,Ti)O3 solid solutions from first principles

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