K. Z. Rushchanskii

Forschungszentrum Jülich

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Marjana Ležaić

Forschungszentrum Jülich

ДМ

Д. М. Берча

Institute of High Pressure Physics

Stefan Blügel

Forschungszentrum Jülich

M. Sznajder

Institute of Physics

S. Kamba

Czech Academy of Sciences, Institute of Physics

Yulian M. Vysochanskii

Uzhhorod National University

F. Sánchez

Institut de Ciència de Materials de Barcelona

Mihaela Gorgoi

Helmholtz-Zentrum Berlin für Materialien und Energie

L. Yu. Kharkhalis

Uzhhorod National University

Manuel Bibès

Université Paris-Saclay

Cooperative Institutions

Forschungszentrum Jülich

Centre National de la Recherche Scientifique

Jülich Aachen Research Alliance

RWTH Aachen University

Czech Academy of Sciences, Institute of Physics

Stadtwerke Jülich (Germany)

Universitat Autònoma de Barcelona

Consejo Superior de Investigaciones Científicas

Czech Academy of Sciences

Université Paris-Saclay

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Stress enhanced self-diffusion in Si: Entropy effect in anisotropic elastic environment

Applied Physics Letters (2008)

K. Z. Rushchanskii Pascal Pochet Frédéric Lançon

We present a multiscale analysis on stress enhanced vacancy-mediated diffusion in strained Si that explicitly includes the Jahn–Teller structural distortion around vacancies. The resulting anisotropy combined with biaxial deformations applied to (100)-oriented films lead to an orientational dependency of the vacancy formation energy. At finite temperatures, it results in a strong entropy effect when thermal activation allows occupancy of high energy defect states. Kinetic Lattice Monte Carlo simulations reveal that the effective activation energy is a strongly nonlinear function of strain at small deformations. At larger deformations, it becomes linear where as the occupancy of the excited states becomes insignificant.

Kinetic Monte Carlo

10.1063/1.2912532

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Citations (7)

Ferroelectricity in (Pb$_y$Sn$_{1-y}$)$_2$P$_2$S$_6$ mixed crystals and random field BEG model

arXiv (Cornell University) (2014)

K. Z. Rushchanskii R. Bilanych A. A. Molnar R. Yevych A. Kohutych

For Sn$_2$P$_2$S$_6$ ferroelectrics the second order phase transitions line is observed until reaching the tricritical point at transition temperature lowering to 250 K by compression. Observed temperature-pressure phase diagram agrees with simulated diagram by MC calculations based on early founded by DFT study local potential for Sn$_2$P$_2$S$_6$ crystals. In addition to the tricritical point, the possibility of disordered and quadrupolar phases occurrence was shown. For mixed crystals with tin by lead substitution, the investigated ultrasound, hypersound and low frequency dielectric properties also reveal appearance of heterophase peculiarities at decreasing of ferroelectric transition temperature below so named "temperature waterline" near 250~K. The tricriticality at similar temperature level also appears in mixed crystals at sulfur by selenium substitution. Such behavior agree with Blume-Emery-Griffiths (BEG) model, that is appropriated for investigated ferroelectric system with three-well local potential for the order parameter (spontaneous polarization) fluctuations.

Tricritical point

Triple point

10.48550/arxiv.1411.2147

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Doped HfO_x nanoclusters: polar and resistive switching in the smallest functional units

physica status solidi (a) (2023)

K. Z. Rushchanskii Marjana Ležaić Stefan Blügel

In the study presented in this article, the impact of proton doping on the structural and electronic properties of hafnium oxide nanoclusters is investigated, with a focus on their potential for use in resistive and polar switching devices. In the results, it is shown that the incorporation of protons can stabilize the cage‐like crystalline structures of clusters, leading to reversible changes in electronic properties by varying oxygen stoichiometry. However, the full coverage of hafnia atoms by hydrogen removes in‐gap states, highlighting the importance of controlled moisture content in redox‐based memristive devices and neuromorphic units. In addition, in this study, the polar properties of these clusters are explored, illustrating possible polar switching in metastable pure , low‐barrier antiferroelectric‐like switching in carbon‐stabilized , and low‐barrier polar switching in . In these findings, the potential of clusters is revealed as active components for next‐generation high‐capacity nonvolatile electronic memory and beyond von Neumann computing in sub‐nanometer scale.

Nanoclusters

Metastability

Non-Volatile Memory

10.1002/pssa.202300404

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Phonon Spectrum of the Layered In4Se3 Crystal

physica status solidi (b) (1999)

Д. М. Берча K. Z. Rushchanskii M. Sznajder

In this paper, we present the results of our calculations of the phonon spectrum for the In4Se3 crystal in the central two-body interaction model without taking into account long-range forces. The model studied here contains five unknown parameters, which were determined from the experimental values of the elastic moduli. The phonon spectrum we obtained contains a large number of low-frequency modes, which deform the acoustic branches. The temperature dependence of the specific heat and of the Debye temperature was determined. The results of our calculations were compared with the experimental data.

Debye model

Debye

Crystal (programming language)

Atmospheric temperature range

Frequency spectrum

10.1002/(sici)1521-3951(199904)212:2<247::aid-pssb247>3.3.co;2-e

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Citations (1)

Pressure-induced toroidal order in molecular Sn$_2$P$_2$S$_6$ ferroelectrics

arXiv (Cornell University) (2024)

K. Z. Rushchanskii M. Medulych V. Liubachko Yulian M. Vysochanskii

For the Sn$_2$P$_2$S$_6$ crystalline compound with a rich temperature--pressure phase diagram that contains the ferroelectric phase, semiconductor-to-metal transition, and superconductive state, \mbox{\textit{ab initio}} molecular dynamics calculations were performed on a single unit cell and on a superstructure using an evolutionary algorithm in combination with density functional theory calculations to study structural transformations resulting from rearrangements in chemical bonds under pressure. The structure models of the pressure-induced lowest energy phases in the molecular Sn$_2$P$_2$S$_6$ crystal demonstrate the possibility of space-arranged chains or rings of P$_2$S$_6$ molecules. Pressure can break P-P bonds of P$_2$S$_6$ molecules, causing one of the phosphorous atoms to displace into the sulfur-formed octahedron and providing another phosphorous atom into an octahedral coordination with two tin atoms and four sulfur atoms. The results of the modeling correlate with the gradual rise of deviation of the pressure dependence of the unit cell volume of the Sn$_2$P$_2$S$_6$ structure, as determined by X-ray diffraction experiments, from the dependence calculated with the Birch-Murnaghan equation of state. It also reveals toroidally ordered local dipoles in the centrosymmetric phase, which may be related to the previously observed superconductivity in the high-pressure metallic phase of Sn$_2$P$_2$S$_6$.

10.48550/arxiv.2408.14179

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EuO Ready for Spintronics---Controlling Epitaxial EuO/Si Spin Interfaces with Passivation Techniques

arXiv (Cornell University) (2015)

Christian Caspers A. Gloskovskii Mihaela Gorgoi Claire Besson M. Luysberg

Epitaxial monolayers of magnetic Europium Oxide (EuO) directly on silicon wafers are perfect candidates for adding spin filter tunneling to silicon technology. However, the inherent chemical reactivity of EuO and Si prevents a straightforward synthesis by reactive molecular beam evaporation (Oxide MBE) without significant contamination of the interface region by Eu silicide and Si oxide formation. We present a solution to this long-standing problem by applying two complementary passivation techniques for the reactive Si (001) surface: \emph{in situ} hydrogen passivation of Si (001) and an oxygen-protective Eu monolayer, without using additional buffer oxides. The interface-engineered EuO/Si spin contacts are chemically analyzed by hard x-ray photoemission spectroscopy, proving that both Eu silicides and Si oxides can be suppressed to the sub-monolayer regime at the same time. A clear EuO \emph{fcc} crystal structure of the 2 nm-EuO/Si (001) spin contacts is evidenced by lateral and cross-sectional electron diffraction techniques. These complementary interface passivations permit highly chemically clean, epitaxial and ferromagnetic EuO/Si (001) spin contacts, rendering possible a one-process \emph{in situ} integration of spin-functional magnetic oxides seamless on silicon wafers.

Passivation

Europium

Source

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Consequences of low-energy non-parabolicity of the dispersion laws for physical parameters and manifestation of new effects in strongly anisotropic crystals

Journal of Physical Studies (2008)

Д. М. Берча L. Yu. Kharkhalis M. Sznajder K. Z. Rushchanskii Ivetta Slipukhina

2 Iнститут фiзики, Унiверситет Жешува, Рейтана, 16а, 35-310, Жешув, Польща (Отримано 28 вересня 2007 р.; в остаточному виглядi 11 листопада 2008 р

10.30970/jps.12.4604

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Citations (2)

Vacancy-mediated diffusion in biaxially strained Si

Applied Physics Letters (2011)

Damien Caliste K. Z. Rushchanskii Pascal Pochet

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Damien Caliste, Konstantin Z. Rushchanskii, Pascal Pochet; Vacancy-mediated diffusion in biaxially strained Si. Appl. Phys. Lett. 17 January 2011; 98 (3): 031908. https://doi.org/10.1063/1.3548547 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioApplied Physics Letters Search Advanced Search |Citation Search

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10.1063/1.3548547

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Citations (15)

Ordering of Oxygen Vacancies and Related Ferroelectric Properties in HfO2−δ

Physical Review Letters (2021)

K. Z. Rushchanskii Stefan Blügel Marjana Ležaić

Using density functional theory combined with an evolutionary algorithm, we investigate ferroelectricity in substoichiometric ${\mathrm{HfO}}_{2\ensuremath{-}\ensuremath{\delta}}$ with fixed composition $\ensuremath{\delta}=0.25$. We find that oxygen vacancies tend to cluster in the form of two-dimensional extended defects, revealing several patterns of local relative arrangements within an energy range of 100 meV per Hf atom. Two lowest-energy patterns result in polar monoclinic structures with different transformation properties. The lowest one elastically transforms to the ferroelectric orthorhombic structure via a shear deformation, overcoming an energy barrier, which is more than twice lower than in the stoichiometric hafnia. The second-lowest structure transforms at smaller volumes to a nonpolar tetragonal one. We discuss the experimentally observed wake-up effect, fatigue, and imprint in ${\mathrm{HfO}}_{2}$-based ferroelectrics in terms of different local ordering of oxygen-vacancy extended defects, which favor specific crystallographic phases.

Monoclinic crystal system

Tetragonal crystal system

Orthorhombic crystal system

10.1103/physrevlett.127.087602

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Citations (45)

Phonon Spectrum of the Layered In4Se3 Crystal

physica status solidi (b) (1999)

Д. М. Берча K. Z. Rushchanskii M. Sznajder

Debye model

Crystal (programming language)

Debye

Atmospheric temperature range

Frequency spectrum

10.1002/(sici)1521-3951(199904)212:2<247::aid-pssb247>3.0.co;2-n

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Citations (17)