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arXiv · 2102.08856

A re-examination of antiferroelectric PbZrO$_3$ and PbHfO$_3$: an 80-atom $Pnam$ structure

J. S. Baker·M. Paściak·J. K. Shenton·P. Vales-Castro·B. Xu·J. Hlinka·P. Márton·R. G. Burkovsky·G. Catalan·A. M. Glazer·D. R. Bowler
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Abstract

First principles density functional theory (DFT) simulations of antiferroelectric (AFE) PbZrO$_3$ and PbHfO$_3$ reveal a dynamical instability in the phonon spectra of their purported low temperature $Pbam$ ground states. This instability doubles the $c$-axis of $Pbam$ and condenses five new small amplitude phonon modes giving rise to an 80-atom $Pnam$ structure. Compared with $Pbam$, the stability of this structure is slightly enhanced and highly reproducible as demonstrated through using different DFT codes and different treatments of electronic exchange & correlation interactions. This suggests that $Pnam$ is a new candidate for the low temperature ground state of both materials. With this finding, we bring parity between the AFE archetypes and recent observations of a very similar AFE phase in doped or electrostatically engineered BiFeO$_3$.

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J. S. Baker, M. Paściak, J. K. Shenton, P. Vales-Castro, B. Xu, J. Hlinka, P. Márton, R. G. Burkovsky, G. Catalan, A. M. Glazer, D. R. Bowler. 2021-02-17. A re-examination of antiferroelectric PbZrO$_3$ and PbHfO$_3$: an 80-atom $Pnam$ structure. https://arxiv.org/abs/2102.08856

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