Surface reconstruction and ferroelectricity in PbTiO${}_3$ thin films

Abstract

Surface and ferroelectric properties of PbTiO${}_3$ thin films are investigated using an interatomic potential approach with parameters computed from first-principles calculations. We show that a model developed for the bulk describes properly the surface properties of PbTiO${}_3$. In particular, the antiferrodistortive surface reconstruction, recently observed from X-ray scattering, is correctly reproduced as a result of the change in the balance of long-range Coulombic and short-range interactions at the surface. The effects of the surface reconstruction on the ferroelectric properties of ultrathin films are investigated. Under the imposed open-circuit electrical boundary conditions, the model gives a critical thickness for ferroelectricity of 4 unit cells. The surface layer, which forms the antiferrodistortive reconstruction, participates in the ferroelectricity. A decrease in the tetragonality of the films leads to the stabilization of a phase with non-vanishing in-plane polarization. A peculiar effect of the surface reconstruction on the in-plane polarization profile is found.

6 pages, 5 figures

References in corpus (6)

• Ferroelectricity and tetragonality in ultrathin PbTiO3 films
• Ultrathin films of ferroelectric solid solutions under residual depolarizing field
• Possible Coexistence of Rotational and Ferroelectric Lattice Distortions in Rhombohedral PZT
• Coexistence of antiferrodistortive and ferroelectric distortions at the PbTiO${}_3$ (001) surface
• Ferroelectricity in Pb(Zr${}_{0.5}$Ti${}_{0.5}$)O${}_3$ thin films: critical thickness and 180${}^{\circ }$ stripe domains
• Properties of Pb(Zr,Ti)O${}_3$ ultrathin films under stress-free and open-circuit electrical boundary conditions

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• Strain game revisited for complex oxide thin-films: Substrate-film thermal expansion mismatch in PbTiO${}_3$
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