Ferroelectric phase transitions in ultrathin films of BaTiO3.
We present molecular dynamics simulations of a realistic model of an ultrathin film of BaTiO3 sandwiched between short-circuited electrodes to determine and understand effects of film thickness, epitaxial strain, and the nature of electrodes on its ferroelectric phase transitions as a function of temperature. We determine a full epitaxial strain-temperature phase diagram in the presence of perfect electrodes. Even with the vanishing depolarization field, we find that ferroelectric phase transitions to states with in-plane and out-of-plane components of polarization exhibit dependence on thickness; it arises from the interactions of local dipoles with their electrostatic images in the presence of electrodes. Secondly, in the presence of relatively bad metal electrodes which only partly compensate the surface charges and depolarization field, a qualitatively different phase with stripelike domains is stabilized at low temperature.
Paul
Jaita
J
TSU, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur PO Bangalore 560 064, India.
Nishimatsu
Takeshi
T
Kawazoe
Yoshiyuki
Y
Waghmare
Umesh V
UV