Abstract Submitted
for the MAR08 Meeting of
The American Physical Society
Improper ferroelectricity in perovskite oxide artificial superlat-
tices MATTHEW DAWBER
1
, NICOLAS STUCKI, CELINE LICHTENSTEIGER,
JEAN-MARC TRISCONE, DPMC, University of Geneva, Switzerland, ERIC
BOUSQUET, PATRICK HERMET, PHILIPPE GHOSEZ, Physique Theorique des
Materiaux, Universite de Liege, Belgium — In paraelectric/ferroelectric heterostruc-
tures with thick constituent layers electrostatics is the dominant interaction be-
tween layers and we have previously demonstrated that the key ferroelectric param-
eters, polarization and critical temperature can be tuned over a very large range
in PbTiO
3
/SrTiO
3
superlattices by varying the ratio of the layer thicknesses [1].
However, as the layers become thinner, a departure from the electrostatic model is
observed, which manifests itself as an unusually high ferroelectric polarization and
transition temperature and a high, but temperature independent, dielectric constant.
Detailed examination of the phase transitions with temperature reveal that along
with these enhanced characteristics there is a fundamental change in the nature of
the ferroelectricity. The microscopic origin of this change, a form of improper ferro-
electricity, is revealed by first principles calculations to occur through a coupling of
oxygen rotations and the polarization mode at the interfaces in the material.
[1] M. Dawber et al., Adv. Mat. (2007)
1
Now at: Physics and Astronomy, SUNY Stony Brook, USA
Matthew Dawber
DPMC, University of Geneva, 24 Quai E.-Ansermet 1211 Geneva 4, Switzerland
Date submitted: 27 Nov 2007 Electronic form version 1.4