logo logo logo

Department of Dielectrics

Institute of Physics of the Czech Academy of Sciences


fig

Theory and simulations

Home Research Highlights Projects Publications People
fzu fig

Zigzag charged domain walls in ferroelectric PbTiO3

We report a theoretical investigation of a charged 180-degree domain wall in ferroelectric PbTiO3, compensated by randomly distributed immobile charge defects. We predict that domain walls form a zigzag pattern and we discuss their properties in a broad interval of compensation-region widths. The zigzag is accompanied by a local polarization rotation which we explain to provide an efficient mechanism for charge compensation. [Phys. Rev. B 107, 094102 (2023)].

(show more)
fzu fig

Multidomain ordered metal–ferroelectric superlattices

By combination of advanced experimental techniques and phase-field simulations, we found that electric dipoles in superlattices, composed of layers of a ferroelectric material separated by thin metallic spacers, form an unusual pattern of nanoscale domains that order in three dimensions. These ferroelectric multidomain ordered superlattices exhibit an outstanding dielectric response and their engineered modulated structural and electronic properties can be controlled using electric field [Nat. Mater. 20, 495 (2021)].

(show more)
fzu fig

Polarization of domain boundaries in SrTiO3 studied by layer group and order-parameter symmetry

Based on a recently developed combination of layer group analysis with order-parameter symmetry, we study the polarity of antiphase domain boundaries (APBs) and ferroelastic twin boundaries (TBs) in SrTiO3 [Phys. Rev. B 102, 184101 (2020)].

(show more)
fzu fig

Curie-Weiss susceptibility in strongly correlated electron systems

We succeeded in identifying a microscopic mechanism combining adequately quantum and thermal fluctuations in metals with strong electron correlations that lead to the genesis of local magnetic moments and the Curie-Weiss susceptibility [Phys. Rev. B 102, 205120 (2020)].

(show more)
fzu fig

Local properties and phase transitions in Sn doped antiferroelectric PbHfO3 single crystal

Pb(Hf0.77Sn0.23)03 crystals were characterized using x-ray diffraction and 119Sn Mossbauer spectroscopy in a wide temperature range. The nature of two intermediate phases, situated between antiferroelectric ground-state and high temperature paraelectric phase, has been unveiled [J. Phys.: Condens. Matter 32, 435402 (2020)].

(show more)
fzu fig

Spatio-temporal distribution of relative Ti-O6 displacements in cubic BaTiO3

BaTiO3 is often considered a model ferroelectric material in which the dielectric properties are defined by the displacements of Ti ions with respect to surrounding oxygen atoms. However, despite the decades of a dedicated research, certain controversies have remained as to the description of collective movements of the Ti ions. We approached this problem using nonoscale-oriented X-ray scattering methods and large-scale atomistic simulations [1]. Together these allowed us to show that the Ti dynamics can be exhaustively explained by phonons excited on a timescale of picoseconds.

(show more)
fzu fig

Domain wall contribution to lattice dynamics and permittivity of BiFeO3

Ferroelectric materials are known for their exceptionally high dielectric permittivity. It turns out, that important part of it originates from a material's complicated microstructure and in particular from interfaces between ferroelectric domains.

(show more)
fzu fig

First-principles-based Landau-Devonshire potential for BiFeO3

We describe a first-principles-based computational strategy for determination of the Landau-Devonshire potential.

(show more)
fzu fig

Existence conditions for ferroaxial materials

All 212 species of structural phase transitions with a macroscopic symmetry breaking were inspected with respect to the simultaneous occurrence of the ferroelastic, ferroelectric, and ferroaxial properties.

(show more)
fzu fig

Ising lines: Natural topological defects within ferroelectric Bloch walls

Phase-field simulations demonstrate that the polarization order-parameter field in the Ginzburg-Landau-Devonshire model of rhombohedral ferroelectric BaTiO3 allows for an interesting linear defect, stable under simple periodic boundary conditions. This linear defect, here called the Ising line, can be described as an about 2-nm-thick intrinsic paraelectric nanorod acting as a highly mobile borderline between finite portions of Bloch-like domain walls of opposite helicity.

(show more)
fzu fig

Phase transition in ferroelectric domain walls of BaTiO3

The seminal paper by Zhirnov (1958 Zh. Eksp. Teor. Fiz. 35 1175–80) explained why the structure of domain walls in ferroelectrics and ferromagnets is so different. We have recently realized that the antiparallel ferroelectric walls in rhombohedral ferroelectric BaTiO3 can be switched between the Ising-like state (typical for ferroelectrics) and a Bloch-like state (unusual for ferroelectric walls but typical for magnetic ones) [see Figure 1] by a compressive epitaxial stress.

(show more)
fzu fig

Dielectric response of a phase transition in domain wall

Computer simulations based on Ginzburg-Landau-Devonshire theory was used to study details of a phase-transition between Ising and Bloch type of a domain wall.

(show more)
fzu fig

Piezoelectric response of nanotwinned ferroelectric perovskites

Computer simulations based on Ginzburg-Landau-Devonshire theory has benn used to investigate piezoelectric properties of tetragonal BaTiO3 crystals. We have shown that piezoelectric response of twinned BaTiO3 increases with increasing density of 90-degree domain walls.

(show more)