0000000000757254
AUTHOR
E.v. Kirichenko
On the theory of thermodynamic properties of geometrically confined disordered ferroelectrics
Abstract We propose a theoretical approach to calculate the thermodynamic properties of thin films fabricated from disordered ferroelectrics. To calculate the above thermodynamic properties, we use so-called random field method, modified for the case of thin films. The essence of modification is the altering of the interaction between impurity dipoles by geometrical confinement. We show that in thin films the ferroelectric phase transition is inhibited as compared to the case of bulk samples. Our theory is generalizable to ferroelectrics of other shapes as well as magnets and multiferroics.
On the theory of domain switching kinetics in ferroelectrics
Abstract We investigate theoretically the polarization switching kinetics in ferroelectrics, both bulk and thin films samples. In such substances, the domain walls are pinned by (usually dipole) defects, which are present also in ordered samples as technologically unavoidable impurities. This random interaction with dipole pinning centers results, in particular, in exponentially broad distribution of switching times. Under supposition of low pinning centers concentration, we derive the distribution function of switching times showing that it is not simply Lorentzian (as it was first suggested by Tagantsev et al. [Phys. Rev. B 66 (2002) 214109]), but is a “square of Lorentzian”, which is due…
The physical mechanisms of relaxation times distribution in inorganic and organic disordered ferroelectrics
Abstract We discuss the physical background for relaxation times distribution in organic and inorganic disordered ferroelectrics. We show that such background is a disorder which is believed to be a reason for relaxor behavior. Due to this disorder the internal electric and elastic fields are of a random nature being characterized by certain distribution function. Having the distribution function f ( E ) of random field E , we can obtain the distribution function of relaxation times F ( τ ) with the help of relation between τ and E . Latter relation can be obtained considering the dynamics of a single electric dipole in a random field created by the ensemble of defects and impurities in a s…