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Ferroelectricity and tetragonality in ultrathin PbTiO3 films

Celine Lichtensteiger·Jean-Marc Triscone·Javier Junquera·Philippe Ghosez
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Abstract

The evolution of tetragonality with thickness has been probed in epitaxial c-axis oriented PbTiO3 films with thicknesses ranging from 500 down to 24 Angstroms. High resolution x-ray pointed out a systematic decrease of the c-axis lattice parameter with decreasing film thickness below 200 Angstroms. Using a first-principles model Hamiltonian approach, the decrease in tetragonality is related to a reduction of the polarization attributed to the presence of a residual unscreened depolarizing field. It is shown that films below 50 Angstroms display a significantly reduced polarization but still remain ferroelectric.

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Celine Lichtensteiger, Jean-Marc Triscone, Javier Junquera, Philippe Ghosez. 2004-10-01. Ferroelectricity and tetragonality in ultrathin PbTiO3 films. https://doi.org/10.1103/physrevlett.94.047603

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