Physics of thin-film ferroelectric oxides

This review covers the important advances in recent years in the physics of thin film ferroelectric oxides, the strongest emphasis being on those aspects particular to ferroelectrics in thin film form. We introduce the current state of development in the application of ferroelectric thin films for electronic devices and discuss the physics relevant for the performance and failure of these devices. Following this we cover the enormous progress that has been made in the first principles computational approach to understanding ferroelectrics. We then discuss in detail the important role that strain plays in determining the properties of epitaxial thin ferroelectric films. Finally, we look at the emerging possibilities for nanoscale ferroelectrics, with particular emphasis on ferroelectrics in non conventional nanoscale geometries.Comment: This is an invited review for Reviews of Modern Physics. We welcome feedback and will endeavour to incorporate comments received promptly into the final versio

Statistical switching kinetics in ferroelectrics

By assuming a more realistic nucleation and polarization reversal scenario we build a new statistical switching model for ferroelectrics, which is different from either the Kolmogorov-Avrami-Ishibashi (KAI) model or the Nucleation-Limited-Switching (NLS) model. After incorporating a time-dependent depolarization field this model gives a good description about the retardation behavior in polycrystalline thin films at medium or low fields, which can not be described by the traditional KAI model. This model predicts correctly n=1 for polycrystalline thin films at high Eappl or ceramic bulks in the ideal case

Unusual behaviour of the ferroelectric polarization in PbTiO3_{3}/SrTiO3_{3} superlattices

Artificial PbTiO$_{3}$/SrTiO$_{3}$ superlattices were constructed using off-axis RF magnetron sputtering. X-ray diffraction and piezoelectric atomic force microscopy were used to study the evolution of the ferroelectric polarization as the ratio of PbTiO$_{3}$ to SrTiO$_{3}$ was changed. For PbTiO$_{3}$ layer thicknesses larger than the 3-unit cells SrTiO$_{3}$ thickness used in the structure, the polarization is found to be reduced as the PbTiO$_{3}$ thickness is decreased. This observation confirms the primary role of the depolarization field in the polarization reduction in thin films. For the samples with ratios of PbTiO$_{3}$ to SrTiO$_{3}$ of less than one a surprising recovery of ferroelectricity that cannot be explained by electrostatic considerations was observed

Folding catastrophes due to viscosity in multiferroic domains : implications for room-temperature multiferroic switching

Unusual domains with curved walls and failure to satisfy the Landau–Lifshitz-Kittel Law are modeled as folding catastrophes (saddle-node bifurcations). This description of ballistic motion in a viscous medium is based upon early work by Dawber et al 2003 Appl. Phys. Lett . 82 436. It suggests that ferroelectric films can exhibit folds or vortex patterns but not both.Publisher PDFPeer reviewe

Negative Differential Resistivity and Positive Temperature Coefficient of Resistivity effect in the diffusion limited current of ferroelectric thin film capacitors

We present a model for the leakage current in ferroelectric thin- film capacitors which explains two of the observed phenomena that have escaped satisfactory explanation, i.e. the occurrence of either a plateau or negative differential resistivity at low voltages, and the observation of a Positive Temperature Coefficient of Resistivity (PTCR) effect in certain samples in the high-voltage regime. The leakage current is modelled by considering a diffusion-limited current process, which in the high-voltage regime recovers the diffusion-limited Schottky relationship of Simmons already shown to be applicable in these systems