The ISAF meeting is actually an important annual international conference gathering scientists all over the world working on both fundamental science and applications of ferroelectrics. The first ISAF meeting was held in 1968; since that time, annual meetings have been hosted all around the world, including Prague in the year 2013 within the joint UFFC, EFTF and ISAF-PFM Symposium, co-organized by the Department of Dielectrics.
Having this in mind, Dalibor got a prestigious award from the community engaged in ferroelectrics and related materials for his experimental work on quantum critical phenomena in multiferroic materials. More specifically, he looks for an experimental proof of the theoretically predicted multiferroic quantum criticality in (Eu,Ba,Sr)TiO₃ solid solution [1]. His PhD research is done under supervision of Dr. Stanislav Kamba and in collaboration with colleagues from Faculty of Mathematics and Physics, Charles University (Prague, Czech Republic) and from CEITEC (Brno, Czech Republic).

References
[1] A. Narayan, A. Cano, A.V. Balatsky, and N. A. Spaldin, Multiferroic quantum criticality, Nature Mater 18 , 223–228 (2019).

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The XXIV Czech-Polish seminar took place in the Giant Mountains (Krkonoše in Czech, Karkonosze in Polish, Riesengebirge in German) in Harrachov (May 23 – 27, 2022) in a warm atmosphere created by 95 participants from 10 countries.

This year, the program of the well-established international conference on Structural and ferroelectric phase transitions (see the highlighted text below) included not only 8 tutorial lectures to stimulate the scientific development of our younger colleagues, but also a Young Researcher Competition. All students had an opportunity to take part in a Clip Session to demonstrate their ability to introduce their research orally in two minutes to a broad audience and in the follow-up poster session. Finally, the best 5 competitors were awarded:

• Vladimir Pushkarev (FZU - Institute of Physics of the Czech Academy of Sciences):
  Charge confinement and band bending in single-crystalline GaAs nanostructures
• Dalibor Repček (FZU - Institute of Physics of the Czech Academy of Sciences):
  Quantum bicriticality tuning in (Eu,Ba,Sr)TiO₃ system
• André Maia (FZU - Institute of Physics of the Czech Academy of Sciences):
  Lattice dynamics and soft-mode friven gerroelectricity in multiferroic BiMn₃Cr₄O₁₂
• Dawid Drozdowski (Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw, Poland):
  Effect of halide mixing on structural and optoelectrical properties of the 3D and 2D methylhydrazinium lead halide perovskites
• Barbara Loska (Institute of Materials Engineering, University of Silesia, Chorzów, Poland):
  Molecular interactions in the twist-bend nematic phase.

History of the Czech-Polish seminar:
The idea of regular scientific meetings of physicists involved in studies of ferroelectrics and phase transitions in Poland and Czechoslovakia followed inevitably from the success of first such an event in Błażejewko in 1979. The Seminar was organized in collaborating of the Department of Dielectrics of the Institute of Physics of Czechoslovak Academy of Sciences and the Ferroelectric Lab of the Institute of Molecular Physics of Polish Academy of Sciences. The Seminars are an international forum for presentation of recent results, unconstrained discussions and initiating of joint studies. This conference series results not only in scientific integration but also in close cooperation and friendship. The bianual event usually brings together about 100–120 participants in a proportion: approximately one third from the Czech Republic, one third from Poland and the rest from other countries.

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To achieve his research goal of developing new multiferroic 2D-sandwich-like materials, Tim has now received a prestigious ERC Starting Grant and a project of the Czech Science Foundation. The grants will allow him to acquire a molecular beam epitaxy apparatus in the new building SOLID21 of the Institute of Physics and to develop his team. In near future, he will be able to produce precise thin multilayers or single-atom layers of multiferroic materials, which might bring him a strong collaboration with other groups of Department of Dielectrics and other departments of the Institute of Physics.

Tim Verhagen obtained bachelor's and master's degree in physics at the Delft University of Technology and PhD at the University of Leiden in the Netherlands. He moved to the Czech Republic in 2014 to work in Jana Kalbáčová Vejpravová's group at the Faculty of Mathematics and Physics of the Charles University and the Institute of Physics of the Czech Academy of Sciences. Since 2020, he has been a researcher at the Institute of Physics of Charles University.

photo: Martin Pinkas, Charles University, Prague
source: https://www.ukforum.cz

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To learn about Vašek's life, please read the obituary by Jirka Hlinka and colleagues from the Department of Dielectrics [1].

[1] J. Hlinka, Obituary: Václav Janovec (1930–2022), Ferroelectrics 599, 1 (2022).

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Best photos coming from Department of Dielectrics in 2021:

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He focused on the phenomenology of ferroelectric phase transitions in crystals and at the beginning of his career became famous for the first description and thermodynamic theory of a new type of so-called triggered ferroelectric phase transition, where a transition parameter with a different symmetry, which would lead to a non-ferroelectric structural phase transition, secondarily triggers also a ferroelectric transition [1]. An interesting and the most common case is when both phase transitions occur at the same temperature in the form of a phase transition of the first type. This work has become widely cited, especially in recent years, when hybrid ferroelectric phase transitions triggered by magnetic transitions appeared.

In later years, together with his colleagues, he also dealt with phase transitions to incommensurably modulated structures and in liquid crystals, but he was very reluctant to publish himself. Nevertheless, he was declared the most versatile and original physicist in the entire department, so a lot of colleagues liked getting involved in discussions with him, although they not always fully understood him.

At the time of the development of computer technology, he even built a simple computer himself. Since 2002, he had worked part-time, but he applied for a pension only when he voluntarily terminated his employment in 2007. In the following years, however, we enjoyed meeting him at Christmas parties.

As it is obvious from the above, Jožka lived very modestly, all his life alone without a family, but he was very popular among his colleagues, and also in the group of his classmates from the Faculty of Mathematics and Physics, who after their studies bought a cottage together, a former rectory in a small village in the area of Český Kras. His main hobby, apart from his work, was bridge, which he had been playing in competitions since the 1970s, and where he was also very popular. We will all miss him.

Reference
[1] J. Holakovský, A New Type of the Ferroelectric Phase Transition, phys. stat. sol. (b) 56, 615 (1973)

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Graphene is a single sheet of carbon atoms forming a two-dimensional infinite honeycomb lattice. For example, a macroscopic ordered stack of such layers forms the graphite; however, the behavior of the graphene single atomic layer is dramatically different from that of graphite.

The electronic properties of graphene are determined by the behavior of charge carriers (electrons and holes); their energy band structure is quite different from typical structures of classical semiconductors or metals and resembles much more the energy scheme of photons.

Depending on the position of the so-called Fermi level (which may be shifted, e.g., due to the nature of the surrounding material and dynamically controlled by illumination or by electric current) graphene can be an excellent conductor or a good insulator. Applications of graphene in electronics and optoelectronics rely on various approaches to the Fermi level tuning by electronic, chemical or optical stimuli.

Free-standing graphene layer is very fragile and is not very useful for practical applications. Therefore, in this study, the group of Petr Kužel focused on graphene layers epitaxially grown on silicon carbide (SiC) substrates. Properties of films prepared under certain conditions approach those of an ideal free-standing graphene layer. By varying the technological conditions, the properties of graphene can be tuned. However, the substrate surface is not perfectly flat even if the greatest care is devoted to its preparation. Instead, it always consists of a set of nanoscopic terraces.

The researchers studied graphene layers using ultrashort laser pulses and terahertz optoelectronic probing (see Fig. 1): an optical pulse excited charge carriers and a delayed ultrashort terahertz pulse tested the state of these carriers. Measured changes in the terahertz pulse shape provided the conductivity spectra, which reflect the distribution of charges within the energy band structure.

The obtained spectra exhibited the so-called localized plasmon resonance, which expresses the collective motion of charge carriers, and which is related to the existence of terraces on the substrate surface. In the investigated graphene samples the build-up and decay of these plasmons on picosecond time scale (1 ps = 10^–12 s) was observed.

In brief, the observed behavior can be described as follows. Before the arrival of the optical laser pulse a significant concentration of equilibrium charge carriers exists in the sample, the graphene film is conducting. Immediately after the optical excitation, the newly generated carriers gain a very high temperature, they exchange energy with equilibrium carriers through elastic scattering, undergo a fast recombination process, and efficiently transfer their energy to the graphene crystal lattice.

During the first picosecond the optically generated carriers practically vanish, and only significantly heated equilibrium carriers remain; the Fermi level exhibits a pronounced decrease with respect to the equilibrium state. The subsequent nonlinear dynamics of plasmons are entirely controlled by the Fermi level of excited carriers through their temperature T_c (see Figure 1). The nonlinear behavior of graphene in this state is a consequence of the unique band structure of graphene which enables very high rate of elastic collisions of carriers. The decay of the nonlinear regime depends on the degree of disorder in the graphene layer. The technological control of the disorder in graphene layers thus allows one to tune the THz response of the material which is important for its optoelectronic applications.

text: Petr Kužel

Reference
[1] V. C. Paingad, J. Kunc, M. Rejhon, I. Rychetský, I. Mohelský, M. Orlita, and P. Kužel, Ultrafast plasmon thermalization in epitaxial graphene probed by time-resolved THz spectroscopy, Adv. Funct. Mater. 31, 2105763 (2021).

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The Falling Walls Lab is a world-class pitch competition that brings together a diverse and interdisciplinary pool of students and researchers, and pioneering innovators. One of the preliminaries of the final Falling Walls Lab in Berlin is yearly organized by the University of Wrocław and is devoted to participants from the Central and Eastern Europe. Three minutes is all it takes to succeed in this competition. What matters is an original idea and the ability to present it in a clear way. In Wroclaw, Karel Tesař has captured attention of Polish scientists by his project Post sternotomy chest pain.

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The front cover (see Fig. 1) shows collective dynamics of spontaneously formed vortices of electric polarization in ferroelectric PbTiO₃ layers of PbTiO₃/SrTiO₃ superlattices which have been investigated by Marek Paściak, Jirka Hlinka, and Christalle Kadlec in a world-wide collaboration (the Argonne National Laboratory, the Pennsylvania State University, the University of California, Berkeley and other American institutions) [1].

The characteristic ultrafast collective polarization dynamics of vortices was discovered by pump-probe experiments, concretely using a terahertz-field excitation and femtosecond X-ray diffraction measurements. Lattice dynamics calculations with first-principle-based interatomic potentials done in Department of Dielectrics unveiled the atomistic picture of the observed excitations (see Fig. 2). In particular, the most coherent and electric-field susceptible mode at the sub-THz frequencies called a vortexon has been recognized as the transverse oscillation of whole polar vortices. The frequency of the vortexon mode has been experimentally and theoretically found to be tunable by temperature or the substrate strain. Moreover, the mode is behind a phase transition from the state in which the vortices are symmetrical to the one where they are staggered. The experiment and calculations prove that THz pulses can excite the polarization state on the nanometer scale which opens opportunities for electric-field-driven data processing in topological structures with ultrahigh speed and density.

Reference
[1] Q. Li, V.A. Stoica, M. Paściak, Y. Zhu, Y. Yuan, T. Yang, M.R. McCarter, S. Das, A.K. Yadav, S. Park, C. Dai, H.J. Lee, Y. Ahn, S.D. Marks, S. Yu, C. Kadlec, T. Sato, M.C. Hoffmann, M. Chollet, M.E. Kozina, S. Nelson, D. Zhu, D.A. Walko, A.M. Lindenberg, P.G. Evans, L.-Q. Chen, R. Ramesh, L.W. Martin, V. Gopalan, J.W. Freeland, J. Hlinka, and H. Wen, Subterahertz collective dynamics of polar vortices, Nature 592, 376 (2021).

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Nowadays mostly studied perovskite materials belong to so-called framework structure materials whose structure is based on units (octahedra, tetrahedra, …) that share some of their corners (or edges) with their neighbors. This book [1] is devoted to the relation between structural organization of such units and unique physical properties of framework structure materials.

One of the important group of framework structure materials long-term studied in the Department of Dielectrics are unfilled tetragonal tungsten-bronze crystals, particularly relaxor ferroelectric strontium barium niobate. The chapter 8 deals mainly with structure relations of NbO₆ octahedra, chemical disorder, phonons and dielectric relaxations in strontium barium niobate.

Reference
[1] E. Buixaderas and J. Dec Phonons and relaxations in unfilled tetragonal tungsten-bronzes, Chap. 8 in "Perovskites and other Framework Structure Materials: new trends and perspectives", editors M.B. Smirnov and P. Saint-Grégoire, Materials and Devices, Vol 5(1), Publ. by Collaborating Academics IP, France (2021).

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The aim of this Special Issue was to promote and highlight scientific and technological contributions from both established and emerging women scientists and engineers in the field of ferroelectrics. The motivation had come from the fact that women remain underrepresented in science, technology, engineering, and mathematics relative to the total population. For example, in the IEEE Ultrasonics, Ferroelectrics and Frequency Control Society, women remain below 10% of the total society members, suggesting that their underrepresentation persists in ferroelectrics research and development activities as well.

Authors in this Special Issue include women at all career stages—including undergraduate students, recent Ph.D. graduates, and those retired from the profession—the common link being the field of ferroelectrics. The collection of contributed articles in the Special Issue covers multiple aspects of processing, structure, theory, and properties of many different ferroelectric materials and devices. E. Buixaderas and M. Paściak reviewed the local structure, phonons, and polarization dynamics of relaxor-ferroelectric (Sr,Ba)Nb₂O₆ (SBN) single crystals using scattering and spectroscopic techniques such as pair distribution function experiments [1]. The schematic of the SBN complex crystal structure was selected for the cover (see Figures 1 and 2).

Reference
[1] E. Buixaderas and M. Paściak, Disorder in Strontium Barium Niobate: Local Structure, Phonons, and Polarization Dynamics, IEEE Trans. Ultrason. Ferroelectr. Freq. Control 68, 314 (2021).

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The concept of order is a cornerstone of condensed matter physics. Atoms order to form crystals, which, in turn, play host to other fascinating and technologically useful ordering phenomena. For example, in ferroelectric crystals, tiny displacements of ions create electric dipoles that order cooperatively to produce a net electric polarization. The orientation of this polarization can be reversed by applying an electric field and serves as the basis for the operation of ferroelectric random access memories that exploit the different orientations of the polarization to store the 1 and 0 bits of information.

Thanks to advances in physical vapour deposition techniques, today, it is possible to create artificially ordered materials, such as superlattices, that consist of very thin sheets of different crystalline materials stacked periodically on top of each other. Artificially layered crystals that combine materials with similar structure but different properties in this way often lead to the emergence of new and unexpected behaviour. For example, in superlattices consisting of periodically alternating ferroelectric and dielectric layers, each just a few nanometres thick, electric dipoles often arrange themselves into complex nanoscale patterns of stripes and whorls. Such dipole patterns are extremely responsive to applied electric fields and give rise to unusual dielectric properties that may prove useful in reducing the power consumption of the billions of transistors in our everyday electronics.

Writing in the journal Nature Materials [1], a collaboration led by Dr. Pavlo Zubko from University College London involving researchers from the United Kingdom, France, Ireland, and Czech Republic, have found that in some superlattices composed of layers of ferroelectric lead titanate (PbTiO₃) separated by thin spacers of metallic or insulating oxides, the electric dipoles form an unusual pattern of nanoscale domains—regions with uniform orientation of the dipoles—that order in three dimensions to create a ‘domain supercrystal’. Under the influence of applied electric field, small displacements of the boundaries between the different domains give rise to large changes in the net electric polarization and thereby enhance the dielectric response of the material along all three spatial directions.

Perhaps an even more interesting aspect of the domain supercrystals is their highly inhomogeneous structure (see figure).  The complex domain patterns in the ferroelectric layers are accompanied by very strong distortions of the crystalline lattice that, in turn, set up a periodic modulation with very large local curvatures in the metallic or insulating spacers. This curvature modifies the local symmetry of the spacer layers, inducing additional polarity that could lead to interesting changes in their properties. Importantly, the curvature can be tuned by application of electric fields and its periodicity can be engineered on demand by adjusting the thicknesses of the ferroelectric layers, making such superlattices an ideal system for exploring curvature-induced phenomena in a variety of insulating, conducting and magnetic materials.

text: P. Zubko

Reference
[1] M. Hadjimichael, Y. Li, E. Zatterin, G. A. Chahine, M. Conroy, K. Moore, E. N. O’ Connell, P. Ondrejkovic, P. Marton, J. Hlinka, U. Bangert, S. Leake, and P. Zubko, Metal–ferroelectric supercrystals with periodically curved metallic layers, Nat. Mater. 20, 495 (2021).

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During the European Researchers' Night, numbers of scientific institutions and infrastructures are animated by popular science activities. The visitors have a unique opportunity to see the labs from inside, to observe some experiments and to listen to lectures on up-to-date topics. Institute of Physics of the Czech Academy of Sciences is one of such sites, and its THz science and technology group is traditionally involved in outreach activities for general public. Its leader Petr Kužel explains specific measures of this year's Researchers' Night: “Undergoing epidemy circumstances did not allow us to organize popular experiments in the THz lab for visitors. Therefore, in a collaboration with our PR division, we created a general public video which introduces the little-known spectral window in the terahertz (THz) range and which gives a flavor of the research and applications with THz radiation.”

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A video created from the best photos presents engaging beauty hidden underneath various microscope objectives. The photo, which was selected as the video thumbnail, presents the beauty of a liquid crystal texture seen by polarized optical microscope, taken by Alexey Bubnov. This picture resembling the Sun’s corona was awarded by the 2^nd place.

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The photonic crystals based on porous silicon were prepared by electrochemical etching and filled with photochromic liquid crystalline (LC) nematic mixture formulated by 4-pentyl-4′-cyanobiphenyl and a specific azobenzene derivative.  These molecules of LC mixture are aligned along the etched channels in silicon plate (see Figure 1). After an UV irradiation (375 nm), a shift of photonic band gap to longer wavelengths by ≈10 nm was observed. This phenomenon was explained by isothermal photoinduced nematic–isotropic phase transition associated with the bent-shaped Z isomer formation of the azobenzene compound. During this transition, effective refractive index slightly increases as the initial homeotropic alignment of LC molecules transforms to the isotropic nonaligned state (see Figure 1). Interestingly, this process between aligned and isotropic states was shown to be completely reversible under visible light action (428 nm) and can be repeated many times. Obtained photonic crystal with photochromic LC composites can be considered as new promising material for photonic applications.

Reference
[1] A. Bobrovsky, S. Svyakhovskiy, A. Bogdanov, V. Shibaev, M. Cigl, V. Hamplová, and A. Bubnov, Photocontrollable Photonic Crystals Based on Porous Silicon Filled with Photochromic Liquid Crystalline Mixture, Adv. Optical Mater. 8, 2001267 (2020).

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Worldwide collaboration including current and former members of the Department of Dielectrics has recently come with a topical review article [1] highlighting new prospects of structural domain walls  - atomically thin objects occurring within the ferroelectric and ferroelastic materials for the same principal reasons as the ordinary knots can be found on ropes and cords.

The paper deals with exotic polarization profiles that can arise at domain walls (see Fig. 1) and with the different mechanisms that lead to domain-wall polarity in non-polar ferroelastic materials like in polar domain walls in non-polar CaTiO₃ (see its domain pattern in Fig. 2). The emergence of energetically degenerate variants of the domain walls themselves suggests the existence of interesting quasi-1D topological defects within such walls. A special attention is paid to the fundamental mechanisms responsible for domain-wall conduction in nonconductive ferroelectrics. Finally, authors are drawing prospects of combination of domain walls with transition regions observed at phase boundaries, homo- and heterointerfaces, and other quasi-2D objects, enabling emergent properties beyond those available in today’s topological systems.

Reference
[1] G. F. Nataf, M. Guennou, J. M. Gregg, D. Meier, J. Hlinka, E. K. H. Salje, and J. Kreisel, Domain-wall engineering and topological defects in ferroelectric and ferroelastic materials, Nat. Rev. Phys. 2, 634 (2020). (show less)

The book covers:

• Comprehensive coverage beyond scientific reviews
• Information is accessible for non-specialists and newcomers
• Explores ideas for future research within the area

(see Table of Contents for more details)

Description:
Technological evolution and revolution are both driven by the discovery of new functionalities, new materials and the design of yet smaller, faster, and more energy-efficient components. Progress is being made at a breathtaking pace, stimulated by the rapidly growing demand for more powerful and readily available information technology. High-speed internet and data-streaming, home automation, tablets and smartphones are now "necessities" for our everyday lives. Consumer expectations for progressively more data storage and exchange appear to be insatiable.
Oxide electronics is a promising and relatively new field that has the potential to trigger major advances in information technology. Oxide interfaces are particularly intriguing. Here, low local symmetry combined with an increased susceptibility to external fields leads to unusual physical properties distinct from those of the homogeneous bulk.
In this context, ferroic domain walls have attracted recent attention as a completely new type of oxide interface. In addition to their functional properties, such walls are spatially mobile and can be created, moved, and erased on demand. This unique degree of flexibility enables domain walls to take an active role in future devices and hold a great potential as multifunctional 2D systems for nanoelectronics. With domain walls as reconfigurable electronic 2D components, a new generation of adaptive nano-technology and flexible circuitry becomes possible, that can be altered and upgraded throughout the lifetime of the device. Thus, what started out as fundamental research, at the limit of accessibility, is finally maturing into a promising concept for next-generation technology.

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The Ferroelectrics Recognition Award recognizes meritorious achievement in the field of Ferroelectricity or related sciences. The award is usually presented at the International Symposium on the Applications of Ferroelectrics (ISAF). This year, the IEEE UFFC Society Ferroelectrics Awards were presented by the Chair of the Awards Committee of IEEE-UFFC, Prof. Roger Whatmore of Imperial College London, UK at IFCS-ISAF 2020 in Keystone, Colorado, USA. The 2020 IEEE UFFC Society Ferroelectrics Awards in three categories were given to:

• Fei Li (Xi’an Jiaotong University): Ferroelectrics Young Investigator Award for “his outstanding contributions to the fundamental understanding of relaxor ferroelectric-lead titanate single crystals and ceramics”.
• Beatriz Noheda (Zernike Institute for Advanced Materials, the Netherlands): Robert E. Newnham Ferroelectrics Award for “her outstanding contributions to the understanding of the giant piezoelectricity in lead zirconate titanate and ferroelectric relaxors, based on her discovery of their low symmetry phases”.
• Jirka Hlinka (Czech Academy of Sciences): Ferroelectrics Recognition Award for “his outstanding contributions to fundamental theoretical and experimental studies of ferroelectrics, relaxor ferroelectrics and multiferroics”.

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The video comes from the series of Undistorted Science.

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The image of the winners will be featured on the cover of an issue of the journal. The authors have also the privilege to write an article to uncover a story behind their winning photos. Karel Tesař and his collaborator Karel Balík (Institute of Rock Structure and Mechanics, Czech Academy of Sciences) contributed by a short article about the state-of-art research on biodegradable implants: Nucleation of corrosion products on H₂ bubbles: A problem for biodegradable magnesium implants?. An interview with Karel Tesař is available on the website of the Institute of Physics of the Czech Academy of Sciences.

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Traditional and chemically simple material BaTiO₃ was grown on NdScO₃ substrates, which allowed researchers to strain the BaTiO₃ film to a peculiar transitional state, showing polarization rotation gradients (see figure) [1,2]. Therefore, in the transitional state, the BaTiO₃ film has different polar phases with different polarization orientation across its thickness. The state is, moreover, stable with temperature. This allows a huge piezoelectric and dielectric response under external electric field in a broad temperature range.

Refrences
[1] A. S. Everhardt, T. Denneulin, A. Grünebohm, Y.-T. Shao, P. Ondrejkovic, S. Zhou, N. Domingo, G. Catalan, J. Hlinka, J.-M. Zuo, S. Matzen, and B. Noheda, Temperature-independent giant dielectric response in transitional BaTiO₃ thin films, Applied Physics Reviews 7, 011402 (2020).
[2] S. Mandel, Research suggests a new class of ferroelectric materials, AIP Scilight. 041101-1 (2020).

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Epitaxial strained thin films of (SrTiO₃)_n-1(BaTiO₃)₁SrO were grown on DyScO₃ substrates using molecular beam epitaxy. The best microwave dielectric properties were discovered in samples with n = 6. Permittivity exhibits huge tuning using electric field and microwave dielectric loss is anomalously low. Unique properties were confirmed using first-principles calculations and by experimental observation of the soft mode behavior in THz region. These films are ideal for components in 5G networks. See you more details in Nat. Mater. (2020).

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Moreover, Vladimira Novotna and Alexey Bububnov obtained the 6^th-12^th place for other remarkable liquid crystal textures captured using polarized light microscope (see Figures 3-5) among 125 photos from 33 participants.

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Selected photos from the celebration:

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The TOPO Workshop series has been established with an ad hoc meeting held in 2015 at the University of New South Wales in Sydney as a reaction of the ferroelectric community to the rising attention towards topological defects like magnetic vortices, Bloch walls, Skyrmions or Merons and to the rising interest in various topological concepts such as winding numbers or homotopy groups. Cross-disciplinary dimension of the workshop with a significant attendance by specialists outside of the ferroelectric community turned out to be extremely stimulating and resulted in subsequent fruitful meetings in Dresden (2016), Leeds (2017) and Natal (2018).
This year’s TOPO followed in the same fashion bringing together the forefront experts as well as young scientists interested in topological aspects of magnetic, superconducting, ferroelectric as well as liquid crystal matter. More than 70 participants from over 15 countries contributed to the intense program comprising over 50 lectures. The detailed program can be found on the conference webpage. Next year’s meeting will be held at the University of California, Berkeley.

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Prof. R. Ramesh has opened new research avenues in ferroelectric nonvolatile memories, colossal magnetoresistive (CMR) oxides and multiferroic oxides, for example, his group in Berkeley demonstrated the large ferroelectric polarization in multiferroic BiFeO3 films and the electric field control of antiferromagnetism and ferromagnetism. His publications are highly cited (over 65,000 citations, H-factor =110). He is a fellow of APS, AAAS & MRS, holder of the Humboldt Senior Scientist Prize, the James McGroddy Prize, the TMS Bardeen Prize, the 2018 IUPAP Magnetism Prize, and the Néel Medal. In 2011, Professor Ramesh was elected to the National Academy of Engineering.

Anotation of the talk: The emergence of the “Internet of Things” and the explosion of Artificial Intelligence/Machine Learning applications are likely to push up significantly the market for microelectronics. The related energy consumption could increase by 20–25%. Thus, looking for a new generation of ultralow power memories and switches is an area of significant current research. Perovskite oxides exhibit a rich spectrum of functional responses, including magnetism, ferroelectricity, highly correlated electron behavior, superconductivity, etc. Over the past decade the oxide community has been exploring the science of such materials in the form of crystals, thin films epitaxial heterostructures and nanostructures with an eye towards lowenergy applications. There exists a small subset of materials – known as multiferroics – which exhibit multiple order parameters at a time. Particularly, the coexistence of ferroelectricity and some form of ordered magnetism (typically antiferromagnetism) has been of major interest due to the evidence that an electric field can control both antiferromagnetism and ferromagnetism at room temperature. Current work in my group is focused on ultralow energy (1 attoJoule/operation) electric field manipulation of magnetism as the backbone for the next generation of ultralow power electronics. In this talk, I will describe our progress to date on this exciting possibility and outline the directions of the future research.

Vladimír Dvořák (1934-2007) was a solid state physicist and the most prominent Czech scientist in the theory of ferroelectricity and structural phase transitions. He was affiliated with the Institute of Physics of the Czech Academy of Sciences in Prague for the whole productive life. He served as its director in 1993–2001 and was the main protagonist of the revolutionary reforms of the Institute after 1989. He was a member of the Learned Society of the Czech Republic since 1995. His personality has strongly influenced the scientific program and development in the Department of Dielectrics of the Institute since the late sixties up to the present. He was a brilliant lecturer and is considered as one of the most respected directors of the Institute.
To commemorate his work and personality, the Institute Physics of the Czech Academy of Sciences decided to organize an annual festive Dvořák lecture, given by prominent internationally renowned scientists in the field related to the research pursued at the Institute..

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The work of Bohuslav Březina and his group greatly contributed to the development of the Department of Dielectrics as experimental research could not be conducted without newly synthesized materials. Observations on newly synthesized compounds stimulated both experimentalists and theoreticians. In such a way his work contributed e.g. to the first international conference on ferroelectric phenomena having been organized in Prague.

He initially grew crystals insoluble in water, prepared from melt, later he started growing water-soluble crystals. Bohuslav Březina’s achievements in this field were applied in industrial production in 1980s; his methods were also patent protected. As an internationally recognized expert in crystal growing, he was invited e.g. to stay at the prestigious Eidgenössische Technische Hochschule in Zürich.

In 1973 a popularising book “Ferroelectrics” (“Feroelektrika”, in Czech) was published by Academia, written by Bohuslav Březina and Petr Glogar. The book is a handy introduction to ferroelectricity, unsurpassed until now.

Bohuslav Březina’s former colleagues will also gratefully remember his kind-hearted personality.

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ABSTRACT:
Domain walls in ferroelectrics are naturally formed 2D solitons with a defined, nm-thick polarization profile stable over macroscopic lateral dimensions. Strong coupling of the polarization gradient with strain drastically changes the material properties within the domain wall thickness. Increasing attention is paid to these mobile interfaces because the characterization tools have recently reached the desired nanoscale resolution, needed to uncover the rich spectrum of new phenomena expected there. We are convinced that some ferroelectrics can also host 1D analogues of domain walls, i.e. spontaneously formed ferroelectric line solitons, similar to the recently experimentally confirmed Bogdanov-Yablonski-type magnetic skyrmion lines. We wish to extend the explorations also to these interesting topological objects and to pave a path to the experimental discovery of the ferroelectric skyrmion phases, analogous to the vortex states in superconductors and skyrmion phases of chiral magnets.

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The winning image set of liquid crystals:

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What do you think an electromagnon is?
Physics can actually be more fun than you think!
Electromagnons are exotic magnetoelectric excitations that appear in particular materials and make their properties more... exciting!
And if you are wondering where you might bump into one of them, the security scanners is the place.
One of these guys has got your back!

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The winning image set of liquid crystals:

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He was involved mainly in the research of domains and domain walls in ferroelectrics. He organized and chaired the 1st International Meeting on Ferroelectricity in Prague in 1966, establishing a series of meetings still active up to date. In 1979 he also initiated a regular series of the Czech–Polish seminars on Ferroelectric and Structural Phase Transitions, still highly popular in both countries. His death arouses world-wide attention in the scientific community and a special session will be devoted to his memory at several international conferences. He can be regarded as a founder of the Czech research on ferroelectrics and the best-known Czech representative in this field.

Jan Petzelt

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The award was announced during the important conference in the field, ECAPD-ISAF-PFM 2016, attended this year by almost 500 scientists and students engaged in fundamental and applied research into ferroelectric and polar dielectrics. Dr. Jan Petzelt studied Faculty of Mathematics and Physics, Charles University in Prague. His scientific career started in 1963 in the Department of Dielectrics, Institute of Physics of the Czechoslovak Academy of Sciences where he accepted the offer to work on a new Fourier infrared spectrometer. In collaboration with Vladimír Dvořák he participated in studying improper ferroelectrics and incommensurately modulated crystals. Jan Petzelt was also engaged in infrared spectroscopy of one- and two-dimensional conductors, ion conductors, dipolar glasses, ceramics for microwave applications, thin ferroelectric films, relaxation ferroelectrics and incipient ferroelectrics, nanocomposites of ferroelectrics and conductive materials etc. Almost every time it was a pioneering work in the field. For example, he was the first to study phonons in thin ferroelectric films. He is an author of more than 350 scientific publications. He was the head of the Department of Dielectrics, Institute of Physics, CAS between 1993 and 2008.

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He is an internationally accepted authority in solid state physics. Throughout his long career at the Institute of Physics of the Czech Academy of Sciences he has contributed to development of physics of dielectric materials. His scientific publications have more than 7000 citations (h-index 46). Since the 1990s he has focused on the investigation of application-attractive materials, particularly ferroelectric thin films and ceramics, relaxor ferroelectrics, novel ferroelectric nanocomposites with considerable dielectric properties and their broadband dielectric spectroscopy.

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Hyde Park Civilization is an interactive programme produced by the Czech Television. It is a programme that deals with the world of science and problems of the modern society.

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