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1.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Shneyder E. I.
Заглавие : The interplay of phonon and magnetic mechanism of pairing in strongly correlated electron system of high-Tc cuprates
Коллективы : International Conference on New Theoreties, Discoveries & Applications of Superconductors and Related Materials, Zhongguancun International Consortium of R&D of Superconductivity Technology Inaugurating Meeting
Место публикации : Seventh International Conference on New Theoreties, Discoveries & Applications of Superconductors and Related Materials and Zhongguancun International Consortium of R&D of Superconductivity Technology Inaugurating Meeting: May 13-16, 2009, Beijing, China. - Ст.S1E0900
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kosyrev N. N., Patrin G. S., Shiyan Ya. G., Volchenko E. N., Yakovchuk V. Yu., Komarov V. A., Semenov S. V.
Заглавие : Influence of the DyxCo1-x–Bi interface on the magnetic properties of DyxCo1-x/Bi/Py three-layer structures
Колич.характеристики :6 с
Место публикации : J. Supercond. Nov. Magn. - 2024. - Vol. 37, Is. 2. - P.419-424. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-024-06690-0. - ISSN 15571947 (eISSN)
Примечания : Cited References: 15. - The authors are grateful to R.Yu. Rudenko for carrying out measurements using an atomic force microscopeThe research was conducted according to the state assignment of the Ministry of Science and Higher Education of the Russian Federation and the Federal State Autonomous Educational Institution of Higher Education Siberian Federal University (No. FSRZ-2023–0008)
Аннотация: The interlayer interactions in multilayer systems with a non-magnetic semimetallic interlayer are great of interest. The magnetic and structural properties of the DyxCo1-x/Bi/Py systems (17 ˂ x ˂ 26 at.%) have been studied. The temperature dependences of magnetization in the range 4.2–300 K were measured for the first time. The influence of the bismuth interlayer thickness on the exchange interaction between the DyCo and Py layers was found as well as the critical value of its thickness. The obtained atypical value of the period of exchange bias oscillations was explained by the formation of bismuth compounds with dysprosium–pnictogenides at bismuth thicknesses below the critical value. The interface was investigated by spectral ellipsometry in the range 2–5 eV. The information on the structure of the surface obtained by atomic force microscopy was used to create a multilayer model for fitting experimental ellipsometric data. Analysis of the optical properties showed that pnictogenide Dy3Bi2 is formed at the interface, which affects the general magnetic state of the samples studied.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aksenov S. V., Kagan M. Yu.
Заглавие : Majorana modes and Fano resonances in Aharonov–Bohm ring with topologically nontrivial superconducting bridge
Колич.характеристики :22 с
Место публикации : J. Low Temp. Phys. - 2024. - Article in press. - ISSN 00222291 (ISSN), DOI 10.1007/s10909-024-03171-5. - ISSN 15737357 (eISSN)
Примечания : Cited References: 46. - We were inspired by Andreev’s seminal contribution in the superconducting nanophysics—the field which started in fact from Josephson effect and Andreev reflection. M. Yu. Kagan thanks the Program for basic research of the National Research University Higher School of Economics for support. The work was partially carried out within the state assignment of Kirensky Institute of Physics. S.V.A. thanks the Foundation for the Advancement of Theoretical Physics and Mathematics "BASIS" for support
Аннотация: We study different resonances (first of all of the Fano type) in the interference device formed by the Aharonov–Bohm ring with superconducting (SC) wire in the topologically nontrivial state playing a role of a bridge between top and bottom arms. We analyze Majorana modes on the ends of the SC wire and show that the collapse of the additional Fano resonance, that is initially induced by transport scheme asymmetry, is connected with the increase of the length of the bridge when the binding energy of the Majorana end modes tends to zero. In local transport regime, the Fano resonances are stable against the change of the transport symmetry. The reasons of both collapse and sustainability are analyzed using a spinless toy model including the Kitaev chain.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Гохфельд, Денис Михайлович, Шаломов С. Ю., Сультимов Д. Б., Петров, Михаил Иванович
Заглавие : Самопроизвольное вращение магнитов, левитирующих над высокотемпературным сверхпроводником
Колич.характеристики :7 с
Место публикации : Сверхпроводимость: фунд. и приклад. исслед. - 2024. - № 1. - С. 34-40. - ISSN 29495644 (ISSN), DOI 10.62539/2949-5644-2024-0-1-34-40; Supercond. Fund. Appl. Res. - ISSN 29495660 (eISSN0
Примечания : Библиогр.: 11. - Авторы выражают благодарность А.Л. Фрейдману за создание сверхпроводящей платформы, С.В. Семенову за помощь с температурными измерениями, а также С.В. Комогорцеву за полезные обсуждения
Аннотация: Левитация постоянного магнита цилиндрической формы над высокотемпературным сверхпроводником, охлаждаемым жидким азотом, сопровождается спонтанными колебаниями, переходящими во вращение. Причиной вращения является неоднородность намагниченности магнита, вызванная градиентом температур вдоль вертикальной оси. Проведен эксперимент по левитации магнитов Nd–Fe–B над композитным высокотемпературным сверхпроводником. Результаты эксперимента подтверждают, что частота вращения зависит от намагниченности верхней и нижней половин магнита. Предложены способы контроля частоты вращения левитирующего магнита.Levitation of a cylindrical permanent magnet over a high-temperature superconductor cooled by liquid nitrogen can be accompanied by spontaneous oscillations and rotation. The reason for spontaneous rotation of the magnet is magnetization inhomogeneity induced by the temperature gradient. An experiment was carried out on the levitation of Nd–Fe–B magnets over a composite high-temperature superconductor. The experimental results confirm that the rotation frequency depends on the difference in the magnetization values in its upper and lower halves of the magnet. Methods for controlling the rotation frequency of a levitating magnet are proposed.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M.
Заглавие : Magnetic flux trapping in porous high-Tc superconductors
Колич.характеристики :4 с
Место публикации : Phys. C: Supercond. Appl. - 2024. - Vol. 619. - Ст.1354486. - ISSN 09214534 (ISSN), DOI 10.1016/j.physc.2024.1354486. - ISSN 18732143 (eISSN)
Примечания : Cited References: 39
Аннотация: Porosity affects the properties of high-Tc superconductors and can improve their performance by enhancing oxygenation, cryocooling, etc. Among other factors, the presence of pores plays a significant role in the process of magnetic flux trapping. Relationships with the porosity manifest in the irreversibility field, the full penetration field, and the remnant magnetization of the samples. To account for the effect of porosity on the trapped magnetic flux into type-II superconductors, a simple toy model is suggested. Generally, as the porosity increases, the trapped flux and related parameters tend to diminish. However, in the case of microscopic samples, porosity can enhance magnetic flux trapping.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kveglis, Ludmila I., Yerbolatuly, Dosym E., Noskov, Fedor M., Komogortsev S. V., Volochaev M. N.
Заглавие : Phases, microstructure and magnetic properties in a severely deformed Cr-Ni–Al alloy
Место публикации : J. Supercond. Nov. Magn. - 2023. - Vol. 36, Is. 4. - P.1249-1255. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-023-06567-8. - ISSN 15571947 (eISSN)
Примечания : Cited References: 22. - The authors express their gratitude to Nurgamit Kantay (East-Kazakhstan University named after S. Amanzholov) for his help in conducting the experiment
Аннотация: The phases, microstructure, and magnetic properties in a severely deformed Cr-Ni–Al alloy have been studied. The eutectic microstructure observed in localized regions of the alloy can be interpreted as a result from the super-Arrhenius relaxation of the alloy. According to X-ray diffraction and magnetometry, the nanosized nickel inclusions in the matrix of the chromium-nickel γ-solid solution are formed. It is shown that, after severe (superplastic) deformation, a unidirectional magnetic anisotropy is induced, which may be associated with the antiferromagnetic coupling between the CrNi2 matrix and the nickel inclusions.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Awana V. P. S., Felner, Israel, Ovchinnikov S. G., Robinson, Jason W. A.
Заглавие : Short note on the observation of ambient condition room temperature superconductivity in nitrogen-doped lutetium hydride
Место публикации : J. Supercond. Nov. Magn. - 2023. - Vol. 36, Is. 4. - P.1085-1086. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-023-06563-y. - ISSN 15571947 (eISSN)
Примечания : Cited References: 21
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M., Semenov S. V., Petrov M. I., Nemtsev I. V., Balaev D. A.
Заглавие : Anisotropy and crystallite misalignment in textured superconductors
Место публикации : J. Supercond. Nov. Magn. - 2023. - Vol. 36, Is. 1. - P.59-65. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-022-06454-8. - ISSN 15571947 (eISSN)
Примечания : Cited References: 21. - This work was supported by the Russian Foundation for Basic Research and the Government of the Krasnoyarsk Territory, Krasnoyarsk Territorial Foundation for Support of Scientific and R&D Activities, project “Superconducting properties of YBCO incorporated by paramagnetic rare-earth elements” No. 20–42–240008
Аннотация: A misalignment of anisotropic crystallites causes small values of anisotropy and decreases the critical current density of textured polycrystalline superconductors. To relate the crystallite misalignment and out-plane anisotropy, the magnetic properties of the textured Bi2223 polycrystalline superconductor were investigated. A distribution of orientation angles of crystallites was determined using different data: scanning electron microscopy images and hysteresis magnetization loops when an external magnetic field was applied at different angles with respect to the texturing plane of the sample. It was demonstrated that the standard deviation of the distribution and the magnetic disorder angle of crystallites in textured samples can be determined from the magnetization data in perpendicular directions. These data may be either the irreversible magnetization measured for two different orientations of the sample or the simultaneously measured magnetization projections parallel and perpendicular to the magnetic field.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Awana V. P. S., Felner I., Ovchinnikov S. G.
Заглавие : New challenges for the Journal of Superconductivity and Novel Magnetism
Место публикации : J. Supercond. Nov. Magn. - 2023. - Vol. 36. - P.1. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-022-06483-3. - ISSN 15571947 (eISSN)
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Awana, V. P. S., Felner, Israel, Ovchinnikov S. G.
Заглавие : Tributes to the memory of professor Vladimir Z. Kresin
Колич.характеристики :4 с
Место публикации :  J. Supercond. Nov. Magn. - 2023. - Vol. 36, Is. 6. - P.1485-1488. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-023-06600-w. - ISSN 15571947 (eISSN)
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Balaev D. A., Semenov S. V., Gokhfeld D. M.
Заглавие : Developing a concept of an effective field in the intergrain medium of a granular superconductor: Effect of the intragrain Meissner currents and Abrikosov vortices trapped in grains on the magnetotransport properties of a Y-Ba-Cu-O granular HTS
Колич.характеристики :18 с
Место публикации : J. Supercond. Nov. Magn. - 2023. - Vol. 36, Is. 7-9. - P.1631-1648. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-023-06608-2. - ISSN 15571947 (eISSN)
Примечания : Cited References: 58. - The authors are grateful to M.I. Petrov, A.D. Balaev, and V.M. Sosnin for fruitful discussions and A.V. Shabanov and I.V. Nemtsev for scanning electron microscopy investigations. The scanning electron microscopy investigations and a part of magnetic measurements (performed on a LakeShore VSM 8604 facility) were carried out at the Krasnoyarsk Regional Center for Collective Use, Krasnoyarsk Scientific Center, Siberian Branch of the Russian Academy of Sciences. The study is performed within the state assignment of Kirensky Institute of Physics
Аннотация: Granular high-temperature superconductors (HTSs) are characterized by the hysteretic field dependences of magnetoresistance R(H) and critical current IC(H). These hysteretic effects are described within the concept of an effective field in the intergrain medium. The effective field is a superposition of external magnetic field H and the field induced by the magnetic moments of superconducting grains into intergrain spacings (grain boundaries). The magnetization of superconducting grains is determined by two contributions: Meissner (shielding) currents (MC) and trapped magnetic fluxes (Abrikosov vortices (AV)). To develop the concept of an effective field in the intergrain medium, the magnetotransport properties (R and IC) have been compared for two cases: (AV) the magnetization of superconducting grains is only determined by the trapped magnetic flux (zero external field) and (MC) HTS grains are in the Meissner state (the external field is weaker than the first critical field of grains). In a set of experiments, the main features of the hysteretic R(H) and M(H) dependences have been illustrated and the external conditions for implementing the AV and MC states have been established. It has been found that the effects of the Abrikosov vortices and intragrain Meissner currents on an effective field in the intergrain medium at the same magnetization values are noticeably different. This is a nontrivial fact that requires a thorough study of the impact of the anisotropy of the superconducting properties of grains on the configuration of the Meissner currents in them, as well as on the orientation of vortices both inside grains and near their surface. We suggest the explanation of observed stronger effect of the Meissner currents on the intergrain medium as compared with the effect of the Abrikosov vortices.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Yu., Aksenov S. V., Turlapov A. V., Ikhsanov R. Sh., Kugel K. I., Mazur E. A., Kuznetsov E. A., Silkin V. M., Burovski E. A.
Заглавие : Formation of droplets of the order parameter and superconductivity in inhomogeneous Fermi–Bose mixtures (Brief review)
Место публикации : JETP Lett. - 2023. - Vol. 117, Is. 10. - P.755-764. - ISSN 00213640 (ISSN), DOI 10.1134/S0021364023600994. - ISSN 10906487 (eISSN)
Примечания : Cited References: 62. - This work was supported by the Russian Foundation for Basic Research (project no. 20-02-00015). M.Yu. Kagan acknowledges the support of the National Research University Higher School of Economics (Program of Basic Research)
Аннотация: The studies of a number of systems treated in terms of an inhomogeneous (spatially separated) Fermi–Bose mixture with superconducting clusters or droplets of the order parameter in a host medium with unpaired normal states are reviewed. A spatially separated Fermi–Bose mixture is relevant to superconducting Ba-KBiO3 bismuth oxides. Droplets of the order parameter can occur in thin films of a dirty metal, described in the framework of the strongly attractive two-dimensional Hubbard model at a low electron density with a clearly pronounced diagonal disorder. The Bose–Einstein condensate droplets are formed in mixtures and dipole gases with an imbalance in the densities of the Fermi and Bose components. The Bose–Einstein condensate clusters also arise at the center or at the periphery of a magnetic trap involving spin-polarized Fermi gases. Exciton and plasmon collapsing droplets can emerge in the presence of the exciton–exciton or plasmon–plasmon interaction. The plasmon contribution to the charge screening in MgB2 leads to the formation of spatially modulated inhomogeneous structures. In metallic hydrogen and metal hydrides, droplets can be formed in shock-wave experiments at the boundary of the first-order phase transition between the metallic and molecular phases. In a spatially separated Fermi–Bose mixture arising in an Aharonov–Bohm interference ring with a superconducting bridge in a topologically nontrivial state, additional Fano resonances may appear and collapse due to the presence of edge Majorana modes in the system.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M.
Заглавие : On estimating the critical current density in polycrystalline superconductors synthesized by solid-state method
Место публикации : J. Supercond. Nov. Magn. - 2023. - Vol. 36, Is. 4. - P.1089-1092. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-023-06575-8. - ISSN 15571947 (eISSN)
Примечания : Cited References: 38
Аннотация: In a recent paper, Zhang et al. [1] studied the effect of a Pb content on the superconducting properties of Bi-2223. Some earlier, Ramirez et al. [2] explored the effect of compaction pressure on the Bi-2212. In both studies, the critical current densities were estimated and compared for a series of polycrystalline superconducting samples. The synthesis conditions for the highest critical current density were claimed in both works. This comment explains that the average granule size should be used instead of the sample size in the Bean formula for the polycrystalline superconductors synthesized by solid-state, sol–gel, electrospinning, and solution blow spinning methods. The corrected estimations for the commented articles conclude that the synthesis conditions affect both the granule size and the intragranular critical current density. The synthesis parameters for the highest critical current density conditions are clarified.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gokhfeld D. M.
Заглавие : Surface barrier of holes drilled in a type-II superconductor
Колич.характеристики :4 с
Место публикации : J. Supercond. Nov. Magn. - 2023. - Vol. 36, Is. 6. - P.1481-1484. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-023-06599-0. - ISSN 15571947 (eISSN)
Примечания : Cited References: 21
Аннотация: Holes drilled in a type-II superconductor trap the magnetic flux. Following Clem’s flux pinning model, we consider surface pinning as a mechanism for compressing the magnetic flux in the holes. Estimations of the trapped magnetic flux demonstrate that the holes with the diameter up to 2 mm are advantageous for bulk single-crystal REBCO samples. The REBCO films and tapes can be improved by the holes with diameter smaller than 10 μm.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Semenok D. V., Troyan I. A., Sadakov A. V., Zhou D., Galasso M., Kvashnin A. G., Ivanova A. G., Kruglov I. A., Bykov A. A., Terent'ev K. Yu., Cherepakhin A. V., Sobolevskiy O. A., Pervakov K. S., Seregin A. Y., Helm T., Forster T., Grockowiak A. D., Tozer S. W., Nakamoto Y., Shimizu K., Pudalov V. M., Lyubutin I. S., Oganov A. R.
Заглавие : Effect of magnetic impurities on superconductivity in LaH10
Место публикации : Adv. Mater. - 2022. - Vol. 34, Is. 42. - Ст.2204038. - ISSN 09359648 (ISSN), DOI 10.1002/adma.202204038. - ISSN 15214095 (eISSN)
Примечания : Cited References: 106. - In situ X-ray diffraction experiments at high pressure were performed on SPring-8, station BL10XU, Sayo, Japan (proposal No. 2020A0576). This work was supported by JSPS KAKENHI Grant Number 20H05644. Low-pressure studies were carried out on a synchrotron source of the Kurchatov institute (KISI-Kurchatov), station RKFM. The high-pressure experiments were supported by the Ministry of Science and Higher Education of the Russian Federation within the state assignment of the FSRC Crystallography and Photonics of the RAS. I.A.T. was supported by the Russian Science Foundation, project No. 22-12-00163. A.R.O. thanks the Russian Science Foundation (grant 19-72-30043). D.V.S. thanks the Russian Foundation for Basic Research (project 20-32-90099). I.A.K. thanks the Russian Science Foundation (grant No. 21-73-10261) for the financial support of the anharmonic phonon density of states calculations and molecular dynamics simulations. SEM, XRF, and XRD studies of the initial alloys were performed using the equipment of the Shared Research Center FSRC Crystallography and Photonics of the RAS. I.A.T. and A.G.I. acknowledge the use of the facilities of the Center for Collective Use “Accelerator Center for Neutron Research of the Structure of Substance and Nuclear Medicine” of the INR RAS for high-pressure cell preparation. The research used resources of the LPI Shared Facility Center. V.M.P acknowledge the support of the state assignment of the Ministry of Science and Higher Education of the Russian Federation (Project No. 0023-2019-0005) and A.V.S. and O.A.S. acknowledge the support of the Russian Science Foundation, grant 22-22-00570. K.S.P. thanks the Russian Foundation for Basic Research (project 19-02-00888). I.A.K. thanks the Russian Science Foundation (grant No. 19-73-00237) for the financial support of the development of T-USPEX method and anharmonic phonon density of states calculation algorithm. S.W.T was supported by NSF Cooperative Agreement No. DMR-1157490/1644779 and by the State of Florida. A.D.G. was supported by T.H. and T.F. funding. The authors acknowledge the support of the HLD at HZDR, member of the European Magnetic Field Laboratory (EMFL). The authors also thank Igor Grishin (Skoltech) for proofreading the manuscript, and Dr. C. Tantardini (University of Tromsø) for calculations using the virtual crystal approximation, and Dr. E. Talantsev (IMP RAS) for useful discussions
Аннотация: Polyhydrides are a novel class of superconducting materials with extremely high critical parameters, which is very promising for sensor applications. On the other hand, a complete experimental study of the best so far known superconductor, lanthanum superhydride LaH10, encounters a serious complication because of the large upper critical magnetic field HC2(0), exceeding 120–160 T. It is found that partial replacement of La atoms by magnetic Nd atoms results in significant suppression of superconductivity in LaH10: each at% of Nd causes a decrease in TC by 10–11 K, helping to control the critical parameters of this compound. Strong pulsed magnetic fields up to 68 T are used to study the Hall effect, magnetoresistance, and the magnetic phase diagram of ternary metal polyhydrides for the first time. Surprisingly, (La,Nd)H10 demonstrates completely linear HC2(T) ∝ |T – TC|, which calls into question the applicability of the Werthamer–Helfand–Hohenberg model for polyhydrides. The suppression of superconductivity in LaH10 by magnetic Nd atoms and the robustness of TC with respect to nonmagnetic impurities (e.g., Y, Al, C) under Anderson's theorem gives new experimental evidence of the isotropic (s-wave) character of conventional electron–phonon pairing in lanthanum decahydride.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Val'kov V. V., Shustin M. S., Aksenov S. V., Zlotnikov A. O., Fedoseev A. D., Mitskan V. A., Kagan M. Yu.
Заглавие : Topological superconductivity and Majorana states in low-dimensional systems
Место публикации : Phys.-Usp. - 2022. - Vol. 65, Is. 1. - P.2-39. - ISSN 10637869 (ISSN), DOI 10.3367/UFNe.2021.03.038950
Примечания : Cited References: 320. - This review was prepared in the framework of the Russian Foundation for Basic Research (RFBR) grant 19-12-50087. Part of the presented results were obtained in the framework of RFBR projects 19-02-00348, 20-32-70059, and 20-02-00015. S V A expresses his gratitude for support through a grant from the President of the Russian Federation, MK-1641.2020.2. A O Z and M S Sh express their gratitude to the Theoretical Physics and Math ematics Advancement Foundation “BASIS”. M Yu K thanks the Program for Basic Research of the NationalResearch University Higher School of Economics for support
Аннотация: We discuss the properties of topologically nontrivial superconducting phases and the conditions for their realization in condensed matter, the criteria for the appearance of elementary Majorana-type excitations in solids, and the corresponding principles and experimental methods for identifying Majorana bound states (MBSs). Along with the well-known Kitaev chain and superconducting nanowire (SW) models with spin-orbit coupling in an external magnetic field, we discuss models of quasi-two-dimensional materials in which MBSs are realized in the presence of noncollinear spin ordering. For finite-length SWs, we demonstrate a cascade of quantum transitions occurring with a change in the magnetic field, accompanied by a change in the fermion parity of the ground state. The corresponding anomalous behavior of the magnetocaloric effect can be used as a tool for identifying MBSs. We devote considerable attention to the analysis of the transport characteristics of devices that contain topologically nontrivial materials. The results of studying the conductance of an Aharonov-Bohm ring whose arms are connected by an SW are discussed in detail. An important feature of this device is the appearance of Fano resonances in the dependence of conductance on the magnetic field when the SW is in a topologically nontrivial phase. We establish a relation between the characteristics of such resonances and the spatial structure of the lowest-energy SW state. The conditions for the occurrence of an MBS in the phase of the coexistence of chiral d+id superconductivity and 120-degree spin ordering are determined in the framework of the t-J-V model on a triangular lattice. We take electron-electron interactions into account in discussing the topological invariants of low-dimensional superconducting materials with noncollinear spin ordering. The formation of Majorana modes in regions with an odd value of a topological ℤ invariant is demonstrated. The spatial structure of these excitations in the Hubbard fermion ensemble is determined.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aksenov S. V.
Заглавие : Manifestation of Majorana modes overlap in the Aharonov-Bohm effect
Место публикации : J. Phys. Condens. Matter. - 2022. - Vol. 34, Is. 25. - Ст.255301. - ISSN 1361648X (ISSN), DOI 10.1088/1361-648X/ac62a7
Примечания : Cited References: 52. - We acknowledge fruitful discussions with A D Fedoseev and M S Shustin. The reported study was funded by Russian Foundation for Basic Research (Project No. 20-02-00015), Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research project ‘Study of edge states in one- and two-dimensional topological superconductors’ (No. 20-42-243005)
Аннотация: One of the key features of the Majorana bound states emerging in topological superconducting (SC) wires is increasing oscillations of their energy under the growth of magnetic field or chemical potential due to concomitant enhancement of hybridization of the Majorana mode wave functions initially localized at the opposite edges of the structure. In this study we found that the other consequence of it is a shift of Aharonov–Bohm (AB) oscillations of linear-response conductance in an interference device where two ends of the SC wire connected with a normal contact via non-SC wires (arms). In addition, it is accompanied by an oscillation period doubling. The numerical calculations for the spinful system are supported by the analytical results for different spinless models allowing to track the conductance evolution as the hybridization of the Majorana modes increases. It is shown that since the coupling between the different arms and normal contact is implemented only via the different-type Majoranas the AB oscillations acquire a fundamental π/2 shift in comparison with the effect for an analogous system of zero-energy quantum dots.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G.
Заглавие : Preface
Место публикации : J. Supercond. Novel Magn. - 2022. - Vol. 35, Is. 4: Road to Room Temperature Superconductivity. - P.957. - ISSN 15571939 (ISSN), DOI 10.1007/s10948-022-06262-0
Аннотация: This Special Issue presents a selection of papers describing recent progress in the search for new materials with Tc approaching room temperature. Two important steps in this direction should be highlighted. In 1986, G. Bednorz and K. A. Müller found that certain oxides containing copper ions displayed high critical temperatures. This was quickly followed by vigorous research and further advances. Several cuprate families with Tc above liquid nitrogen temperature and even above 100 K were identified. Since cuprates have a layered structure, their discovery has stimulated intensive theoretical studies of systems with reduced dimensionality. In the meantime, the key question regarding the mechanism of high Tc superconductivity in the cuprates remains controversial. The next important step was taken in 2015 by M. Eremets and his group who demonstrated the superconducting state in the hydride H3S with Tc exceeding 200 K. This phenomenon was observed under megabar pressure: an increase in pressure leads to structural transitions. The existence of the high Tc phase had been predicted by D. Duan and her collaborators in 2014. As for the mechanism, it is presently generally accepted that high Tc in the hydrides is caused by the strong coupling of electrons with high-frequency hydrogen vibrations. Thus, materials with near-room-temperature critical temperatures have been achieved, but they require the use of extremely high-pressure techniques. The Special Issue also contains a paper by C. W. Chu and his collaborators. Prof. Chu and his group have made key contributions to the study of cuprates, including the discovery of the famous YBa2Cu3O7, the first material with Tc approaching 100 K. In this issue, they describe novel studies of materials capable of retaining the high-Tc state after the removal of high pressure. Unfortunately, any sample housed in a diamond anvil cell is not practical for applications. It is therefore valuable to pursue alternative approaches. Two papers in this Special Issue describe other promising directions. V. V. Kresin and his group have provided evidence for high-temperature superconductivity in size-selected metal nanoclusters with a quantized electronic level structure. I. Felner describes studies of sulfur-doped amorphous carbon and other interesting observations. All papers in this Special Issue have been submitted by invitation. We are grateful to all authors for their contributions.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Koblischka, Michael R., Koblischka-Veneva, Anjela, Gokhfeld D. M., Naik, S. Pavan Kumar, Nouailhetas, Quentin, Berger, Kevin, Douine, Bruno
Заглавие : Flux pinning docking interfaces in satellites using superconducting foams as trapped field magnets
Коллективы : ANRFrench National Research Agency (ANR); DFGGerman Research Foundation (DFG)European Commission [ANR-17-CE05-0030, DFG-ANR Ko2323-10]
Место публикации : IEEE Trans. Appl. Supercond. - 2022. - Vol. 32, Is. 4. - Ст.4900105. - ISSN 1051-8223, DOI 10.1109/TASC.2022.3147734. - ISSN 1558-2515(eISSN)
Примечания : Cited References: 44. - This work was supported in part by SUPERFOAM international project funded by ANR and DFG under Grants ANR-17-CE05-0030 and DFG-ANR Ko2323-10.
Предметные рубрики: BULK
RECONFIGURATION
MAGNETIZATION
Аннотация: Flux-Pinning Docking Interfaces (FPDI) in satellite systems were developed using bulk superconductors and permanent magnets in previous works. However, such FPDIs have limited magnetic field strength, consist of heavy-weight material, and can only be used with a single purpose, i.e., as chasing or docking satellite. Replacing the magnetic material in the FPDI by a trapped field (TF)-magnet would enable the interface to operate for both purposes, i.e., generating a (stronger) magnetic field and trapping it. We show the requirements for such a system and discuss the possible gains when using a TF-FPDI in satellites. To reduce the system weight, the use of superconducting foams as superconducting material is discussed in detail. Furthermore, the use of superconducting foams, the size of which can be easily upscaled, may also comprise the function of the damping material, so even more weight could be saved for the payload.
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20.

Вид документа : Статья из журнала
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Автор(ы) : Abramova G. M., Freydman A. L., Eremin E. V., Pogoreltcev E. I., Velikanov D. A.
Заглавие : Dielectric and magnetic anomalies in α-MnS single crystals at applied magnetic fIelds
Место публикации : J. Supercond. Nov. Magn. - 2022. - Vol. 35, Is. 1. - P.277-281. - ISSN 1557-1939, DOI 10.1007/s10948-021-06045-z. - ISSN 1557-1947(eISSN)
Примечания : Cited References: 22
Предметные рубрики: MAGNETOSTRICTION
ANISOTROPY
Аннотация: Temperature and magnetic field dependences of the magnetic susceptibility and dielectric permittivity of the α-MnS single crystal with NaCl structure are first investigated at around Neel temperature and at 4.2 K and H up to 70 kOe. A relation between the investigated properties was established. The founded phenomena can be due to the magnetostriction or magnetoelastic mechanism and the spin-dependent dipole moment.
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