Ferroelectricity and tetragonality in ultrathin PbTiO3 films.
The evolution of tetragonality with thickness has been probed in epitaxial c-axis oriented PbTiO3 films with thicknesses ranging from 500 down to 24 A. High resolution x ray pointed out a systematic decrease of the c-axis lattice parameter with decreasing film thickness below 200 A. 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 A display a significantly reduced polarization but still remain ferroelectric.
Lichtensteiger
Céline
C
DPMC, Université de Genéve, 24 Quai Ernest-Ansermet, CH-1211 Genéve 4, Switzerland. Celine.Lichtensteiger@physics.unige.ch
Triscone
Jean-Marc
JM
Junquera
Javier
J
Ghosez
Philippe
P