Научные публикации
Canonical Monte Carlo multispin cluster method
Journal of Computational and Applied Mathematics.
Volume 427, 1 August 2023, 115153, 138; https://doi.org/10.1016/j.cam.2023.115153
by Kseniia Makarova, Aleksandr Makarov, Vladislav Strongin, Iuliia Titovets, Yuriy Shevchenko, Vitalii Kapitan, Alexey Rybin, Dmitrii Kapitan, Alena Korol, Egor Vasiliev, Pavel Ovchinnikov, Konstantin Soldatov, Viacheslav Trukhin, Konstantin Nefedev
Abstract
We present a new Canonical Multispin-flip Cluster Monte Carlo algorithm for Ising model and describe efficient implementations for hybrid supercomputer. Our method takes advantage of the computing architecture for parallel and multi-threaded operations and uses a sequential cluster state update scheme. Due to the peculiarity of the implementation, the method is more effective for models with a restricted radius of interaction. It is based on combining a random selection of spin cluster by the Monte Carlo method with a complete enumeration of the all states of the selected cluster. To show how it works we applied our method to models of interacting magnetic Ising-moments: ferromagnetic Ising model, the Edwards–Anderson spin glass model, dipolar spin ice on hexagonal and pentagonal Cairo lattices.
https://www.sciencedirect.com/science/article/pii/S0377042723000973
Functionally Gradient Material Fabrication Based on Cr, Ti, Fe, Ni, Co, Cu Metal Layers via Spark Plasma Sintering
Coatings 2023, 13(1), 138; https://doi.org/10.3390/coatings13010138
by Oleg O. Shichalin, Evgeniy K. Papynov, Igor Yu. Buravlev, Anastasiya A. Buravleva, Sergey V. Chuklinov, Ekaterina A. Gridasova, Anton V. Pogodaev, Valreiia A. Nepomnyushchaya, Zlata E. Kornakova, Alexey O. Lembikov, Danila V. Gritsuk, Olesya V. Kapustina, Sofia S. Gribanova and Yun Shi
Abstract
The paper presents a method of obtaining functionally graded material (FGM) of heterogeneous (layered) type based on joined metals Cr-Ti-Fe-Co-Ni-Cu using spark plasma sintering (SPS) technology. The structure, elemental and phase composition of FGM obtained on the basis of joined metals with different values of the temperature coefficient of linear expansion (CTLE) were studied by SEM, EDS and XRD methods with regard to the phase states of the alloy system. Based on the Vickers microhardness data, the evaluation of the mechanical characteristics of FGM in the whole sample body and locally at the contact boundaries of the joined metals was carried out. The results of the study are new and represent a potential for FGM, as well as functionally graded coatings (FGC), which have special physical, chemical and mechanical properties and are highly demanded for the manufacture of structures and products for industrial applications.
https://www.mdpi.com/2079-6412/13/1/138
Ionizing radiation source-open type fabrication using additive technology and spark plasma sintering
Ceramics International – Volume 49, Issue 2, 15 January 2023, Pages 3083-3087
https://doi.org/10.1016/j.ceramint.2022.11.020
E.K. Papynov, O.O. Shichalin, A.A. Belov, I. Yu. Buravlev, A.S. Portnyagin, A.G. Kozlov, E.A. Gridasova, I.G. Tananaev, V.I.Sergienko
Abstract
The paper presents an original method for open-type ionizing radiation source (IRS) fabrication by the means of spark plasma sintering-reactive synthesis (SPS-RS) of SrTiO3 ceramics as an active zone component reinforced by the titanium alloy framework produced by additive technology. Rapid heating regimes of SPS-RS are described with the focus on fabrication of perovskite-phase SrTiO3 crystalline ceramics integrated within the reinforcing Ti–Al–V framework yielding defect- and pore-free monolith. The product is characterized by the excellent crack resistance, Vickers microhardness (480–554 HV), and hydrolytic stability (leaching rate as low as 10−5 g/cm2·day). Presented results show bright prospects for high-tech radioisotope production in the form of open-type IRS meeting the requirements of international standards.
https://www.sciencedirect.com/science/article/pii/S0272884222040044
Order and disorder, crossovers, and phase transitions in dipolar artificial spin ice on the Cairo lattice
Phys. Rev. E 106, 064105 – Published 5 December 2022
DOI:https://doi.org/10.1103/PhysRevE.106.064105
Yuriy Shevchenko, Vladislav Strongin, Vitalii Kapitan, Konstantin Soldatov, Aleksandr Makarov, Mihail Padalko, Roman Volotovskii, and Konstantin Nefedev
Abstract
We study the thermodynamic properties of the magnetic dipolar spin ice on a 2D pentagonal Cairo lattice by using the numerical Metropolis and the complete enumeration methods. We use the model of point Ising-like dipoles considering long-range interactions with up to 100 nearest neighbors and with periodic boundary conditions. There are two explicit peaks both in the temperature behavior of the heat capacity and in the magnetic susceptibility. The low-temperature peak is caused only by long-range interactions and is not present in the model where each dipole interacts only with four nearest neighbors. The height of the peak depends logarithmically on the quantity of dipoles, which indicates a phase transition. The nature of the low-temperature phase transition is related to the transformation from order to disorder in orthogonal sublattices while maintaining the spin ice state and the spin ice rule in the sublattice of crosses. The high-temperature heat capacity peak is associated with the melting of spin ice, i.e., with the crossover from spin ice to paramagnetic chaos. Its height is constant and does not depend on the quantity of dipoles. It is shown that the choice of the radius of the dipole-dipole interaction has a significant effect on the statistical properties of the model. The model may even show the appearance of the long-range order and the phase transition in the case of long-range interaction or its absence in the case of short-range interaction.
https://journals.aps.org/pre/abstract/10.1103/PhysRevE.106.064105
Magnetic phase transition in an amorphous alloy: The theory of random fields of exchange interaction
Journal of Magnetism and Magnetic Materials
Volume 564, Part 2, 15 December 2022, 170172
https://doi.org/10.1016/j.jmmm.2022.170172
V.Belokon, R.Lapenkov, O.Dyachenko
Abstract
In this study, an attempt was made to sequentially calculate the Curie temperature of iron-containing alloys based on the theory of random fields of exchange interaction. This method makes it possible to determine the conditions for the occurrence of ferromagnetism in an amorphous alloy depending on the concentration of exchange-interacting ions, their Holschmidt radius, and the type of crystal lattice of the transition metal.
https://www.sciencedirect.com/science/article/pii/S0304885322010575?via%3Dihub
Titania coatings decorated with ultra-thin gold films: Optical, electrochemical and photoelectrochemical properties
Journal of Alloys and Compounds
Volume 913, 25 August 2022, 165320
https://doi.org/10.1016/j.jallcom.2022.165320
M.S.Vasilyeva, I.V.Lukiyanchuk, K.A.Sergeeva, A.A.Sergeev, E.V.Shchitovskaya, bV.S.Egorkin, V.G.Kuryavii, A.Yu.Ustinov, S.L.Sinebryukhov, S.V.Gnedenkov
Abstract
The coating with a porous structure, having a good adhesion to the substrate and containing titanium dioxide in the modifications of rutile and anatase, has been obtained by plasma electrolytic oxidation of VT1–0 technically pure titanium in a 0.1 M neutral aqueous solution of Na2SO4. Gold 10-nm-layer has been deposited on surface by electron-beam evaporation to obtain Ti/TiO2/Au composite. This gold layer consists of 5 nm gold nanoparticles, which has been determined based on the coherent scattering regions for the diffraction peak (111) using the Debye-Scherrer method. Deposition of 10-nm gold layer on the surface of Ti/TiO2 results in increase in photocurrent densities from 3·10−9 A/cm2 to 4·10−6 A/cm2. Calculation from the slopes of the Mott-Schottky plots enable one to estimate the number of charge carriers (donors) and the flat band potential vs Ag/AgCl, which are ND = 3.9·1019 cm−3, Efb = – 0.14 V for Ti/TiO2 and ND = 3.0·1020 cm−3, Efb = – 0.4 V for Ti/TiO2/Au composite.
https://www.sciencedirect.com/science/article/pii/S092583882201711X
Reaction synthesis of SrTiO3 mineral-like ceramics for strontium-90 immobilization via additional in-situ synchrotron studies
Ceramics International
Volume 48, Issue 14, 15 July 2022, Pages 19597-19605
https://doi.org/10.1016/j.ceramint.2022.03.068
O.O. Shichalin, A.A. Belov, A.P. Zavyalov, E.K. Papynov, S.A. Azon, A.N. Fedorets, I. Yu. Buravlev, M.I.Balanov, I.G.Tananaev, Yun Shi, Qian Zhang, Mingjun Niu, Wentao Liu, A.S.Portnyagin
Abstract
The paper presents spark plasma sintering-reaction synthesis (SPS-RS) of SrTiO3-based mineral-like ceramics with a perovskite structure, which is promising for immobilization of Sr-90 radionuclides. Detailed time-resolved study of phase transformations taking place in the reactive mixture (SrCO3 and TiO2) within 20–1000 °C temperature range was conducted using both in situ heating synchrotron XRD and TGA. Structure and composition dependence on consolidation temperature was revealed by the means of SEM and EDX. We determined optimal temperature conditions for rapid formation of SrTiO3 ceramics with density – 4.49 g cm−3, Vickers hardness – up to 6.2 GPa, compressive strength – 279 MPa, and strontium leaching rate of 10−5–10−6 g cm−2·day. These results clearly show strong applied potential of the presented material for radioactive waste management and isotope production fields.
https://www.sciencedirect.com/science/article/pii/S0272884222008446?via%3Dihub
Synthesis and spark plasma sintering of solid-state matrices based on calcium silicate for 60Co immobilization
Journal of Alloys and Compounds
Volume 912, 15 August 2022, 165233
https://doi.org/10.1016/j.jallcom.2022.165233
O.O.Shichalin, S.B.Yarusova, A.I.Ivanets, E.K.Papynov, A.A.Belov, S.A.Azon, I. YuBuravlev, A.E.Panasenko, P.A.Zadorozhny, V.Yu. Mayorov, D. Kh. Shlyk, V.A.Nepomnyushchaya, O.V.Kapustina, A.E.Ivanova, A.A.Buravleva, E.B.Merkulov, P.S.Gordienko
Abstract
An effective sorption material for the immobilization of cobalt radionuclides into highly safe and reliable solid-state matrices is proposed. The resulting silicate sorbent СaSiO3 had an amorphous mesoporous structure (ABET 53 m2/g) and a sorption capacity Co ions of 3.32 mmol/g. The physico-chemical characteristics of the СaCoSi2O6 sample obtained after Co2+ ions sorption were studied using XRD, N2 and Ar adsorption-desorption, SEM-EDX and TG/DTA methods. Solid-state silicate matrices characterized by high density values (2.86–3.16 g/cm3), compressive strength (150–637 MPa) and Vickers microhardness (1.80–5.25 GPa) were obtained by spark plasma sintering (SPS). The sample obtained at 1000 °C had the lowest values of Co2+ ions leaching (RCo ~10−7 g/(cm2×day)) and diffusion coefficient (De 1.73 ×10−17 cm2/s) from silicate matrices. Thus, the obtained СaCoSi2O6 silicate matrices saturated with Co ions comply with the regulatory requirements of GOST R 50926–96 and ANSI/ANS 16.1 for 60Co immobilization.
https://www.sciencedirect.com/science/article/pii/S0925838822016243?via%3Dihub
Spark Plasma Sintering of WC-Based 10wt%Co Hard Alloy: A Study of Sintering Kinetics and Solid-Phase Processes
Materials 2022, 15(3), 1091;https://doi.org/10.3390/ma15031091
Anastasia A. Buravleva, Alexander N. Fedorets, Anastasia A. Vornovskikh, Alexey V. Ognev, Valeria A. Nepomnyushchaya, Vladimir N. Sakhnevich, Aleksey O. Lembikov, Zlata E. Kornakova, Olesya V. Kapustina, Anna E. Tarabanova, Victor P. Reva, Igor Yu. Buravlev
Abstract
The paper describes the method for producing WC-10wt%Co hard alloy with 99.6% of the theoretical density and a Vickers hardness of ~1400 HV 0.5. Experimental data on densification dynamics, phase composition, morphology, mechanical properties, and grain size distribution of WC-10%wtCo using spark plasma sintering (SPS) within the range of 1000–1200 °C are presented. The high quality of the product is provided by the advanced method of high-speed powder mixture SPS-consolidation at achieving a high degree of densification with minimal calculated grain growth at 1200 °C.
https://www.mdpi.com/1996-1944/15/3/1091
Interwire and Intrawire Magnetostatic Interactions in Fe-Au Barcode Nanowires with Alternating Ferromagnetically Strong and Weak Segments
First published: 03 October 2022https://doi.org/10.1002/smll.202203555
Aleksei Yu. Samardak,Yoo Sang Jeon, Vadim Yu. Samardak, Alexey G. Kozlov, Kirill A. Rogachev, Alexey V. Ognev, Eunjin Jeong, Gyu Won Kim, Min Jun Ko, Alexander S. Samardak,Young Keun Kim
Abstract
Metallic barcode nanowires (BNWs) composed of repeating heterogeneous segments fabricated by template-assisted electrodeposition can offer extended functionality in magnetic, electrical, mechanical, and biomedical applications. The authors consider such nanostructures as a 3D system of magnetically interacting elements with magnetic behavior strongly affected by complex magnetostatic interactions. This study discusses the influence of geometrical parameters of segments on the character of their interactions and the overall magnetic behavior of the array of BNWs having alternating magnetization, because the Fe and Au segments are made of Fe-Au alloys with high and low magnetizations. By controlling the applied current densities and the elapsed time in the electrodeposition, the dimension of the Fe-Au BNWs can be regulated. This study reveals that the influence of the length of magnetically weak Au segments on the interaction field between nanowires is different for samples with magnetically strong 100 and 200 nm long Fe segments using the first-order reversal curve (FORC) diagram method. With the help of micromagnetic simulations, three types of magnetostatic interactions in the BNW arrays are discovered and analy. This study demonstrates that the dominating type of interaction depends on the geometric parameters of the Fe and Au segments and the interwire and intrawire distances.
https://onlinelibrary.wiley.com/doi/10.1002/smll.202203555
Field-Free Spin–Orbit Torque Switching Enabled by the Interlayer Dzyaloshinskii–Moriya Interaction
Nano Lett. 2022, 22, 17, 6857–6865
Publication Date:July 18, 2022
https://doi.org/10.1021/acs.nanolett.1c04786
Wenqing He, Caihua Wan*, Cuixiu Zheng, Yizhan Wang, Xiao Wang, Tianyi Ma, Yuqiang Wang, Chenyang Guo, Xuming Luo, Maksim E. Stebliy, Guoqiang Yu, Yaowen Liu, Alexey V. Ognev, Alexander S. Samardak, and Xiufeng Han*
Abstract
Perpendicularly magnetized structures that are switchable using a spin current under field-free conditions can potentially be applied in spin–orbit torque magnetic random-access memory (SOT-MRAM). Several structures have been developed; however, new structures with a simple stack structure and MRAM compatibility are urgently needed. Herein, a typical structure in a perpendicular spin-transfer torque MRAM, the Pt/Co multilayer and its synthetic antiferromagnetic counterpart with perpendicular magnetic anisotropy, was observed to possess an intrinsic interlayer chiral interaction between neighboring magnetic layers, namely, the interlayer Dzyaloshinskii–Moriya interaction (DMI) effect. Furthermore, using a current parallel to the eigenvector of the interlayer DMI, we switched the perpendicular magnetization of both structures without a magnetic field, owing to the additional symmetry breaking introduced by the interlayer DMI. This SOT switching scheme realized in the Pt/Co multilayer and its synthetic antiferromagnet structure may open a new avenue toward practical perpendicular SOT-MRAM and other SOT devices.
https://pubs.acs.org/doi/10.1021/acs.nanolett.1c04786
Field-free superconducting diode effect in noncentrosymmetric superconductor/ferromagnet multilayers
Nature Nanotechnologyvolume 17, pages 823–828 (2022) Cite this article
Hideki Narita, Jun Ishizuka, Ryo Kawarazaki, Daisuke Kan, Yoichi Shiota, Takahiro Moriyama, Yuichi Shimakawa, Alexey V. Ognev, Alexander S. Samardak, Youichi Yanase & Teruo Ono
Abstract
The diode effect is fundamental to electronic devices and is widely used in rectifiers and a.c.–d.c. converters. At low temperatures, however, conventional semiconductor diodes possess a high resistivity, which yields energy loss and heating during operation. The superconducting diode effect (SDE) which relies on broken inversion symmetry in a superconductor, may mitigate this obstacle: in one direction, a zero-resistance supercurrent can flow through the diode, but for the opposite direction of current flow, the device enters the normal state with ohmic resistance. The application of a magnetic field can induce SDE in Nb/V/Ta superlattices with a polar structure, in superconducting devices with asymmetric patterning of pinning centres or in superconductor/ferromagnet hybrid devices with induced vortices. The need for an external magnetic field limits their practical application. Recently, a field-free SDE was observed in a NbSe2/Nb3Br8/NbSe2 junction; it originates from asymmetric Josephson tunnelling that is induced by the Nb3Br8 barrier and the associated NbSe2/Nb3Br8 interfaces. Here, we present another implementation of zero-field SDE using noncentrosymmetric [Nb/V/Co/V/Ta]20 multilayers. The magnetic layers provide the necessary symmetry breaking, and we can tune the SDE by adjusting the structural parameters, such as the constituent elements, film thickness, stacking order and number of repetitions. We control the polarity of the SDE through the magnetization direction of the ferromagnetic layers. Artificially stacked structures, such as the one used in this work, are of particular interest as they are compatible with microfabrication techniques and can be integrated with devices such as Josephson junctions. Energy-loss-free SDEs as presented in this work may therefore enable novel non-volatile memories and logic circuits with ultralow power consumption.
https://www.nature.com/articles/s41565-022-01159-4
Новое поколение фотокатализаторов видимого света – висмутаты щелочноземельных металлов: синтез, состав, структура и свойства
Journal of Photochemistry & Photobiology, C: Photochemistry Reviews 50 (2022) 100501https://doi.org/10.1016/j.jphotochemrev.2022.100501
Полупроводниковые материалы, содержащие висмут, привлекают внимание исследователей в течение последних нескольких десятилетий в связи с их высокой фотокаталитической активностью в различных реакциях и высокой эффективностью фотоэлектрического преобразования солнечной энергии. Этот интерес также обусловлен тем, что как правило висмутсодержащие полупроводники имеют достаточно малую ширину запрещенной зоны, что делает их чувствительными к излучению в видимой области спектра. Среди различных висмутсодержащих полупроводниковых материалов в отдельную группу выделяют висмутаты щелочноземельных металлов (магния, кальция, стронция и бария). В данной статье проводится обзор исследований по известным методам получения висмутатов различных щелочноземельных металлов с дальнейшим анализом их состава, строения и фотокаталитической активности.
Авторы:
Штарев Дмитрий Сергеевич, в.н.с. лаборатории фотоактивных полупроводниковых материалов ИНТиПМ ДВФУ (Россия)
Ник Серпоне, профессор университета Павии (Италия).
Топологически нетривиальные спиновые текстуры в тонких магнитных пленках
Журнал: «Физика металлов и металловедение»Том: 123 Номер: 3 Год: 2022 Страницы: 260-283
DOI: 10.31857/S0015323022030093;
Представлены результаты передовых исследований в развивающейся области современного магнетизма и спинтроники – топологического наномагнетизма, в рамках которого изучается природа нетривиальных спиновых текстур и топологических эффектов. Наибольшее внимание уделяется киральным спиновым текстурам, недавно открытым в тонких магнитных пленках, таким как скирмионы, скирмиониумы, антискирмионы и другие, их статическим и динамическим свойствам, методам их зарождения и управления, а также перспективам создания функциональных устройств на их основе. Интерес к одно-, двух- и трехмерным магнитным структурам обусловлен не только спектром новых свойств и эффектов, требующих проведения теоретических и экспериментальных исследований, но и потенциалом их практического использования. Возможность получения малых и стабильных магнитных текстур, таких как скирмионы, открывает перспективы для создания новых типов оперативной памяти, конфигурируемой логики и развития нейроморфных вычислений.
Авторы: Cамардак А.С., Колесников А.Г., Давыденко А.В., Стеблий М.Е., Огнев А.В.
Температурная зависимость скорости движения доменной стенки в ферримагнитной структуре Tb/CoFeB/MgO
Journal of Magnetism and Magnetic Materials. Volume 553, 1 July 2022, 169251;
https://doi.org/10.1016/j.jmmm.2022.169251
Одним из возможных направлений развития электроники является использование магнитоупорядоченных сред для задач обработки и хранения информации. Область науки, которая занимается этими подходом, называется спинтроника, и одной из ее актуальных задач является исследование процессов и состояний, реализуемых в ферримагнитных средах. В простейшем случае ферримагнетики – это сплавы состоящие из атомов двух сортов, каждый из которых обладает магнитным моментом. Практически значимой особенностью ферримагнетиков является возможность управления их магнитными свойствами посредствам изменения взаимной концентрации атомов или температуры образца. Изменяя эти параметры, можно добиться состояния с нулевым магнитным или угловым моментом. Первое соответствует максимальной стабильности системы, так как она становится невосприимчива к магнитным полям, второе – максимальной скорости движения доменной стенки.
Влияние ферромагнитного слоя с плоскостной анизотропией на возможность токоиндуцированного перемагничивания в многослойной структуре
Appl. Phys. Lett. 120, 122402 (2022); https://doi.org/10.1063/5.0079400
Разработка надежных методов локального управления ориентации намагниченности посредствам пропускания электрического тока является одной из ключевых задач спинтроники. В работе проведено экспериментально исследование одного из возможных подходов для решения этой задачи посредствам использование двух магнитносвязанных слоев. Пропускание тока через структуру содержащую бислой “тяжелый металл”/ферромагнетик (ТМ/ФМ), может приводить к генерации тока спин-поляризованных электронов из слоя ТМ в слой ФМ в следствие спинового эффекта Холла. Действие такого тока может приводить к переключению ориентации намагниченности в слое ФМ, при условии нарушения симметрии состояния, которое проще всего создается с помощью постоянного магнитного поля в плоскости образца [2]. Практическая сложность реализации такого механизма привела к разработке нескольких методов, позволяющих отказаться от необходимости использования внешнего поля.
Нейросеть «Ограниченная машина Больцмана» помогает в изучении спиновых стекол
Статья на сайте журнала «Письма в ЖЭТФ»: http://jetpletters.ru/ps/2371/article_35091.shtml
Статья «Вычисление основных состояний спиновых стекол, используя ограниченную машину Больцмана» принята к публикации в 8 номере «Письма в ЖЭТФ» – ведущего российского журнала по теоретической физике. Ее авторы – сотрудники Лаборатории суперкомпьютерных и квантовых вычислений и Лаборатории статистической физики конденсированных сред, Департамента теоретической физики и интеллектуальных технологий ИНТиПМ, студенты и аспиранты ДВФУ.