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arXiv · 0812.0960

Ideal barriers to polarization reversal and domain-wall motion in strained ferroelectric thin films

S. P. Beckman·Xinjie Wang·Karin M. Rabe·David Vanderbilt
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Abstract

The ideal intrinsic barriers to domain switching in c-phase PbTiO_3 (PTO), PbZrO_3 (PZO), and PbZr_{1-x}Ti_xO_3 (PZT) are investigated via first-principles computational methods. The effects of epitaxial strain on the atomic structure, ferroelectric response, barrier to coherent domain reversal, domain-wall energy, and barrier to domain-wall translation are studied. It is found that PTO has a larger polarization, but smaller energy barrier to domain reversal, than PZO. Consequentially the idealized coercive field is over two times smaller in PTO than PZO. The Ti--O bond length is more sensitive to strain than the other bonds in the crystals. This results in the polarization and domain-wall energy in PTO having greater sensitivity to strain than in PZO. Two ordered phases of PZT are considered, the rock-salt structure and a (100) PTO/PZO superlattice. In these simple structures we find that the ferroelectric properties do not obey Vergard's law, but instead can be approximated as an average over individual 5-atom unit cells.

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S. P. Beckman, Xinjie Wang, Karin M. Rabe, David Vanderbilt. 2008-12-04. Ideal barriers to polarization reversal and domain-wall motion in strained ferroelectric thin films. https://doi.org/10.1103/physrevb.79.144124

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