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Your search keyword '"Shapovalov, Konstantin"' showing total 3 results
Start Over Author "Shapovalov, Konstantin" Topic domain walls
3 results on '"Shapovalov, Konstantin"'

1. The Third Dimension of Ferroelectric Domain Walls.

Author

Roede, Erik D, Shapovalov, Konstantin, Moran, Thomas J, Mosberg, Aleksander B, Yan, Zewu, Bourret, Edith, Cano, Andres, Huey, Bryan D, van Helvoort, Antonius TJ, and Meier, Dennis

Subjects
ErMnO3, domain walls, ferroelectric materials, quasi-2D systems, tomography, Bioengineering, Physical Sciences, Chemical Sciences, Engineering, Nanoscience & Nanotechnology
Abstract

Ferroelectric domain walls are quasi-2D systems that show great promise for the development of nonvolatile memory, memristor technology, and electronic components with ultrasmall feature size. Electric fields, for example, can change the domain wall orientation relative to the spontaneous polarization and switch between resistive and conductive states, controlling the electrical current. Being embedded in a 3D material, however, the domain walls are not perfectly flat and can form networks, which leads to complex physical structures. In this work, the importance of the nanoscale structure for the emergent transport properties is demonstrated, studying electronic conduction in the 3D network of neutral and charged domain walls in ErMnO3 . By combining tomographic microscopy techniques and finite element modeling, the contribution of domain walls within the bulk is clarified and the significance of curvature effects for the local conduction is shown down to the nanoscale. The findings provide insights into the propagation of electrical currents in domain wall networks, reveal additional degrees of freedom for their control, and provide quantitative guidelines for the design of domain-wall-based technology.

Published
2022

2. Topological Defects in Hexagonal Manganites: Inner Structure and Emergent Electrostatics.

Author

Holtz, Megan E., Shapovalov, Konstantin, Mundy, Julia A., Chang, Celesta S., Zewu Yan, Bourret, Edith, Muller, David A., Meier, Dennis, and Cano, Andrés

Subjects
*MANGANITE, *ELECTROSTATICS, *OXIDE minerals, *MANGANESE ores, *COUPLING reactions (Chemistry), *SCANNING transmission electron microscopy
Abstract

Diverse topological defects arise in hexagonal manganites, such as ferroelectric vortices, as well as neutral and charged domain walls. The topological defects are intriguing because their low symmetry enables unusual couplings between structural, charge, and spin degrees of freedom, holding great potential for novel types of functional 2D and 1D systems. Despite the considerable advances in analyzing the different topological defects in hexagonal manganites, the understanding of their key intrinsic properties is still rather limited and disconnected. In particular, a rapidly increasing number of structural variants is reported without clarifying their relation, leading to a zoo of seemingly unrelated topological textures. Here, we combine picometer-precise scanning-transmission-electron microscopy with Landau theory modeling to clarify the inner structure of topological defects in Er1-xZrxMnO3. By performing a comprehensive parametrization of the inner atomic defect structure, we demonstrate that one primary length scale drives the morphology of both vortices and domain walls. Our findings lead to a unifying general picture of this type of structural topological defects. We further derive novel fundamental and universal properties, such as unusual bound-charge distributions and electrostatics at the ferroelectric vortex cores with emergent U(1) symmetry. [ABSTRACT FROM AUTHOR]

Published
2017
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3. Thin-film-specific elastic effects in ferroelectric domain structures

Author

Shapovalov, Konstantin, Tagantsev, Alexander, and Setter, Nava

Subjects
Condensed Matter::Materials Science, domain wall conductivity, Ferroelectricity, thin films, domain walls, elastic domain structures control, antiphase boundary
Abstract

An essential feature of ferroelectric thin films is the presence in them of domain structures. In order to efficiently implement ferroelectric films into potential new ferroelectrics-based devices, it is of high interest to understand the behaviour of domain structures. Some properties of ferroelectric domain structures, such as internal structure of domain walls, orientation of domain walls, which were investigated and formulated for bulk systems, are typically believed to be applicable to thin films as well. In this work, importance of thin-film-specific effects on domain structure formation is discussed. It is shown that in thin films nonferroelastic domain walls may interact by elastic means on distances far exceeding the domain wall width, which is sometimes considered as the maximal range of their interaction. Theoretical study of films of practical interest shows that the force of elastic repulsion between the walls can be strong enough to be important during the polarization switching and for control of nonferroelastic domain structures. Further, this work discusses mechanisms of ferroelastic domain wall orientation specific to thin films. Typically, when a ferroelastic wall orients violating the condition of mechanical compatibility of the domains, macroscopic elastic fields appear leading to increase of the energy of the system restraining the deviation of the wall from the compatible state. It is shown that in thin films this increase of the energy can be small enough to allow competition with other contributions to the energy, such as domain wall self-energy, leading to large deviations of the wall orientation from its compatible state. Another investigated mechanism of ferroelastic domain wall orientation is interference of elastic fields generated by an incompatible wall with the film-substrate misfit stresses. A system is investigated where such interference, which leads to reduction of elastic energy of the structure, results in deviation of the wall from its compatible state, violating the domain wall electric neutrality as well. Using this result, the concept of elasticity-driven generation of charged conductive domain walls is developed; the concept is supported by reports of experimental observation of metallic-like domain wall conduction in Pb(Zr,Ti)O3 films. A theoretical description is provided for ferroelastic structures with narrow domain inclusions into dominant domain state. It is obtained that in sparse structures the domain periodicity follows linear dependence on the film thickness, not the classical Kittel-like square root dependence. Equilibrium parameters of the domain structure, such as periodicity of the structure, width of the narrow inclusions, are obtained; the results for Pb(Zr,Ti)O3 films are compared with experimental observations of the films. Finally, antiphase boundary with local ferroelectricity in antiferroelectric is investigated. The mechanical response of such boundary on external electric field is modelled. It is shown that the electric field gradient can be used as the driving force for displacement of the boundary. Conditions for displacement of the boundary sufficient for Scanning Probe Microscopy observations are formulated.

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