We present an approach to the size effect problem in ferroelectric-electrode systems which combines first-principles calculations and phenomenological theory. The parameters of the model can be extracted from calculations on ultrathin films, while experimentally verifiable predictions can be made on thick films. We illustrate the approach for the case ofâ€¦ (More)

We report a first-principles investigation of ultrathin BaTiO(3) films with SrRuO(3) electrodes. We find that the ionic relaxations in the metal-oxide electrode play a crucial role in stabilizing the ferroelectric phase. Comparison with frozen-phonon calculations shows that the degree of softness of the SrRuO(3) lattice has an essential impact on theâ€¦ (More)

We present a model for reverse domain nucleation in ferroelectrics, which takes into account ferroelectric-electrode coupling in both homogeneous and random cases. The model provides a solution to the coercivity paradox--i.e., the large discrepancy between the observed and predicted coercive fields, common to many systems. We demonstrate the possibility ofâ€¦ (More)

Phase transitions in condensed matter are affected by a small volume and/or restricted geometry of the systems. The understanding of the relevant size effects is of practical importance when such systems are used as functional materials in the form of small particles and thin films. At the origin of these effects, one can distinguish two contributions. Oneâ€¦ (More)

The integration of ferroelectrics in electronic devices requires that they be used in the form of thin films, which implies that for such systems finite-size effects related to the presence of a ferroelectric-electrode interface become important. In this thesis, a number of theoretical studies are presented on the properties of metal-ferroelectric-metalâ€¦ (More)