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Polarization coupling in ferroelectric multilayers M. B. Okatan,1 J. V. Mantese,2 and S. P. Alpay1,3,*

Summary: Polarization coupling in ferroelectric multilayers
M. B. Okatan,1 J. V. Mantese,2 and S. P. Alpay1,3,*
1Department of Chemical, Materials, and Biomolecular Engineering, Materials Science and Engineering Program,
University of Connecticut, Storrs, Connecticut 06269, USA
2United Technologies Research Center, East Hartford, Connecticut 06108, USA
3Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA
Received 23 December 2008; revised manuscript received 12 March 2009; published 21 May 2009
A thermodynamic model was developed to understand the role of charge compensation at the interlayer
interfaces in compositionally graded monodomain ferroelectric multilayers. The polarization mismatch be-
tween the ferroelectric layers generates depoling fields with the polarization in each layer varying from its bulk
uncoupled value as to adapt to the electrical boundary conditions. By treating the strength of the electrostatic
field as a phenomenological parameter, it is shown that if there are localized charges to compensate for the
polarization mismatch and relax the depolarization fields, ferroelectric layers behave independently of each
other and exhibit a dielectric response that can be described as the sum of their corresponding intrinsic
uncoupled dielectric properties. For perfectly insulating heterostructures with no localized charges, the depo-
larization field is minimized by lowering the polarization difference between layers, yielding a ferroelectric
multilayer that behaves as if it were a single ferroelectric material. There exists an optimum value of coupling
strength at which average polarization of the multilayer is maximized. Furthermore, ferroelectric multilayers
may display a colossal dielectric response dependant upon the interlayer electrostatic interactions.
DOI: 10.1103/PhysRevB.79.174113 PACS number s : 77.80.Bh, 77.22.Ej


Source: Alpay, S. Pamir - Department of Materials Science and Engineering, University of Connecticut


Collections: Materials Science