Theory and simulations
Our effort is devoted to fundamental theoretical investigation of dielectric materials using different calculation and simulation techniques. In particular, we aim at ferroelectrics and relaxors, which are important in a wide range of applications (e.g. in actuators, sensors in medical devices or in telecommunication), mostly due to their large piezoelectric and dielectric response; but they possess a lot more applicable properties. We aim at elucidating the mechanisms driving their exceptional performance, and using the acquired knowledge to participate in further tuning of the materials for particular purposes/applications or even in the development of new materials.
It turns out that a common feature of these material is the presence of an electric polarization, its heterogeneity on different scales, and the possibility to switch the polarization by an electric field or mechanical pressure. The switching is facilitated by a typically large density of interfaces between regions with similar polarization (usually called domains). Importantly, there is strong coupling between polarization and tilt. The material properties are also strongly influenced by chemical disorder, defects, the presence of boundaries in polycrystals, etc. All this makes the target material group extremely versatile and suited for applications, but on the other hand extremely challenging theoretically and experimentally.
In order to capture the important physics, we address the materials on different length scales from quantum-mechanical calculations through atomistic empirical-potential based simulations up to phenomenological models which allow to capture interaction of large domains. In this multiscale approach we study the material structure, dynamical properties, as well as electromechanical properties stemming from intrinsic (perfect crystal) as well as extrinsic (e.g. due to domain interfaces or defects) contributions.
As a part of the Department of dielectrics we participate in the interpretation of spectroscopic experiments (mostly related to dynamics of solids). Besides that, we also have plenty of collaborations with theoretical and experimental groups abroad as well as in Czech Republic and participate in the explanation of experiments and testing of ideas obtained elsewhere. Finally, we also publish our own theoretical predictions and ideas, which are yet to be experimentally confirmed.