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Borodianskyi, Evgenii A.ORCID iD iconorcid.org/0000-0003-4815-5856
Alternative names
Publications (10 of 11) Show all publications
Kapran, O. M., Morari, R., Golod, T., Borodianskyi, E. A., Boian, V., Prepelita, A., . . . Krasnov, V. M. (2021). In situ transport characterization of magnetic states in Nb/Co superconductor/ferromagnet heterostructures. Beilstein Journal of Nanotechnology, 12, 913-923
Open this publication in new window or tab >>In situ transport characterization of magnetic states in Nb/Co superconductor/ferromagnet heterostructures
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2021 (English)In: Beilstein Journal of Nanotechnology, ISSN 2190-4286, Vol. 12, p. 913-923Article in journal (Refereed) Published
Abstract [en]

Employment of the non-trivial proximity effect in superconductor/ferromagnet (S/F) heterostructures for the creation of novel superconducting devices requires accurate control of magnetic states in complex thin-film multilayers. In this work, we study experimentally in-plane transport properties of microstructured Nb/Co multilayers. We apply various transport characterization techniques, including magnetoresistance, Hall effect, and the first-order-reversal-curves (FORC) analysis. We demonstrate how FORC can be used for detailed in situ characterization of magnetic states. It reveals that upon reduction of the external field, the magnetization in ferromagnetic layers first rotates in a coherent scissor-like manner, then switches abruptly into the antiparallel state and after that splits into the polydomain state, which gradually turns into the opposite parallel state. The polydomain state is manifested by a profound enhancement of resistance caused by a flux-flow phenomenon, triggered by domain stray fields. The scissor state represents the noncollinear magnetic state in which the unconventional odd-frequency spin-triplet order parameter should appear. The non-hysteretic nature of this state allows for reversible tuning of the magnetic orientation. Thus, we identify the range of parameters and the procedure for in situ control of devices based on S/F heterostructures.

Keywords
cryogenic computing, devices exploiting spin polarized transport or integrated magnetic field, spin-valve, superconducting multilayers, superconducting spintronics
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-197400 (URN)10.3762/bjnano.12.68 (DOI)000686077600001 ()34497739 (PubMedID)2-s2.0-85115887526 (Scopus ID)
Available from: 2021-10-04 Created: 2021-10-04 Last updated: 2022-03-30Bibliographically approved
Kalenyuk, A. A., Borodianskyi, E. A., Kordyuk, A. A. & Krasnov, V. M. (2021). Influence of the Fermi surface geometry on the Josephson effect between iron-pnictide and conventional superconductors. Physical Review B, 103(21), Article ID 214507.
Open this publication in new window or tab >>Influence of the Fermi surface geometry on the Josephson effect between iron-pnictide and conventional superconductors
2021 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 103, no 21, article id 214507Article in journal (Refereed) Published
Abstract [en]

We study hybrid Josephson junctions between a multiband Ba1-xNaxFe2As2 iron-pnictide and Nb. We observe that the insertion of a Cu interlayer in such junctions leads to a dramatic enhancement of the IcRn product, despite the weaker proximity-induced superconductivity of Cu. This counterintuitive phenomenon is attributed to the differences in Fermi surface geometries of Nb and Cu, which affect the selectivity of tunneling in sign-reversal s± bands of pnictide. Our results indicate that the sensitivity to Fermi surface geometries provides a new tool for phase-sensitive studies and paves the way to conscious Fermi surface engineering of pnictide junctions.

Keywords
Unconventional superconductivity, Tunneling phenomena
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:su:diva-196119 (URN)10.1103/PhysRevB.103.214507 (DOI)000661190200005 ()2-s2.0-85108204581 (Scopus ID)
Available from: 2021-09-03 Created: 2021-09-03 Last updated: 2022-03-29Bibliographically approved
Cattaneo, R., Borodianskyi, E. A., Kalenyuk, A. A. & Krasnov, V. M. (2021). Superconducting Terahertz Sources with 12% Power Efficiency [Letter to the editor]. Physical Review Applied, 16(6), Article ID L061001.
Open this publication in new window or tab >>Superconducting Terahertz Sources with 12% Power Efficiency
2021 (English)In: Physical Review Applied, E-ISSN 2331-7019, Vol. 16, no 6, article id L061001Article in journal, Letter (Refereed) Published
Abstract [en]

Low power efficiency is one of the main problems of terahertz (THz) sources, colloquially known as “the THz gap.” In this work we present prototypes of THz devices based on whisker crystals of a high-temperature superconductor Bi2Sr2CaCu2O8+δ with a record high-radiation power efficiency of 12% at a frequency of approximately 4 THz. We employ various on- and off-chip detection techniques and, in particular, use the radiative cooling phenomenon for accurate evaluation of the emission power. We conclude that such devices can be used for creation of tunable, monochromatic, cw, compact, and power-efficient THz sources.

Keywords
Coherent THz sources, Superconductivity, Josephson effect
National Category
Condensed Matter Physics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-200556 (URN)10.1103/PhysRevApplied.16.L061001 (DOI)000731544400003 ()2-s2.0-85121578410 (Scopus ID)
Available from: 2022-01-07 Created: 2022-01-07 Last updated: 2022-11-17Bibliographically approved
Galin, M. A., Rudau, F., Borodianskyi, E. A., Kurin, V. V., Koelle, D., Kleiner, R., . . . Klushin, A. M. (2020). Direct Visualization of Phase-Locking of Large Josephson Junction Arrays by Surface Electromagnetic Waves. Physical Review Applied, 14(2), Article ID 024051.
Open this publication in new window or tab >>Direct Visualization of Phase-Locking of Large Josephson Junction Arrays by Surface Electromagnetic Waves
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2020 (English)In: Physical Review Applied, E-ISSN 2331-7019, Vol. 14, no 2, article id 024051Article in journal (Refereed) Published
Abstract [en]

Phase-locking of oscillators leads to super-radiant amplification of the emission power. This is particularly important for development of terahertz sources, which suffer from low emission efficiency. In this work we study large Josephson junction arrays containing several thousand Nb-based junctions. Using low-temperature scanning laser microscopy, we observe that at certain bias conditions two-dimensional standing-wave patterns are formed, manifesting themselves as global synchronization of the arrays. Analysis of standing waves indicates that they are formed by surface plasmon-type electromagnetic waves propagating at the electrode-substrate interface. Thus, we demonstrate that surface waves provide an effective mechanism for long-range coupling and phase-locking of large junction arrays.

Keywords
Superconductivity, THz sources, Josephson junctions
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:su:diva-185345 (URN)10.1103/PhysRevApplied.14.024051 (DOI)000561848600002 ()2-s2.0-85091973486 (Scopus ID)
Available from: 2020-12-03 Created: 2020-12-03 Last updated: 2022-11-08Bibliographically approved
Borodianskyi, I. (2020). Superradiant THz wave emission from arrays of Josephson junctions. (Doctoral dissertation). Stockholm: Department of Physics, Stockholm University
Open this publication in new window or tab >>Superradiant THz wave emission from arrays of Josephson junctions
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

High-power, continuous-wave, compact and tunable THz sources are needed for a large variety of applications. Development of power-efficient sources of electromagnetic radiation in the 0.1-10 THz range is a difficult technological problem, known as the “THz gap.” Josephson junctions allow creation of monochromatic THz sources with an inherently broad range of tunability. However, emission power from a single junction is too small. It can be amplified in a coherent superradiant manner by phase-locking of many junctions. In this case, the emission power should increase as a square of the number of phase-locked junctions.The aim of this thesis is to study a possibility of achieving coherent super-radiant emission with significant power and frequency tunability from Joseph-son junction arrays. Two types of devices are studied, based either on stacks (one-dimensional arrays) of intrinsic Josephson junctions naturally formed in single crystals of high-temperature cuprate superconductor Bi2Sr2CaCu2O8+x, or two-dimensional arrays of artificial low-temperature superconducting Nb/NbSi/Nb junctions. Micron-size junctions are fabricated using micro- and nanofabrication tools.The first chapter of this thesis describes the theory of Josephson junctions and how mutual coupling between Josephson junctions can lead to self-syn-chronization, facilitating the superradiant emission of electromagnetic radia-tion. The second chapter is focused on the technical aspects of this work, with detailed descriptions of sample fabrication and experimental techniques. The third chapter presents main results and discussion. It is demonstrated that de-vices based on high-Tc cuprates allow tunable emission in a very broad fre-quency range 1-11 THz. For low- Tc junction arrays synchronization of up to 9000 junctions is successfully achieved. It is argued that an unconventional traveling-waves mechanism facilitates the phase-locking of such huge arrays. The obtained results confirm a possibility of creation of high-power, continu-ous-wave, compact and tunable THz sources, based on arrays of Josephson junctions.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2020. p. 67
Keywords
Josephson junction, Superconductor, ThZ emission, high-Tc
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-181234 (URN)978-91-7911-178-6 (ISBN)978-91-7911-179-3 (ISBN)
Public defence
2020-09-09, sal FR4, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Available from: 2020-08-17 Created: 2020-04-28 Last updated: 2022-03-04Bibliographically approved
de Andrés Prada, R., Golod, T., Kapran, O. M., Borodianskyi, E. A., Bernhard, C. & Krasnov, V. M. (2019). Memory-functionality superconductor/ferromagnet/superconductor junctions based on the high-Tc cuprate superconductors YBa2Cu3O7−x and the colossal magnetoresistive manganite ferromagnets La2/3X1/3MnO3+δ(X=Ca,Sr). Physical Review B, 99(21), Article ID 214510.
Open this publication in new window or tab >>Memory-functionality superconductor/ferromagnet/superconductor junctions based on the high-Tc cuprate superconductors YBa2Cu3O7−x and the colossal magnetoresistive manganite ferromagnets La2/3X1/3MnO3+δ(X=Ca,Sr)
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2019 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 99, no 21, article id 214510Article in journal (Refereed) Published
Abstract [en]

Complex oxides exhibit a variety of unusual physical properties, which can be used for designing novel electronic devices. Here we fabricate and study experimentally nanoscale superconductor/ferromagnet/ superconductor junctions with the high-Tc cuprate superconductors YBa2Cu3O7−x and the colossal magnetoresistive (CMR) manganite ferromagnets La2/3X1/3MnO3+δ(X=CaorSr). We demonstrate that in a broad temperature range the magnetization of a manganite nanoparticle, forming the junction interface, switches abruptly in a monodomain manner. The CMR phenomenon translates the magnetization loop into a hysteretic magnetoresistance loop. The latter facilitates a memory functionality of such a junction with just a single CMR ferromagnetic layer. The orientation of the magnetization (stored information) can be read out by simply measuring the junction resistance in a finite magnetic field. The CMR facilitates a large readout signal in a small applied field. We argue that such a simple single-layer CMR junction can operate as a memory cell both in the superconducting state at cryogenic temperatures and in the normal state up to room temperature.

Keywords
High-temperature superconductivity, collosal magnetoresistance, oxide electronics
National Category
Condensed Matter Physics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-171104 (URN)10.1103/PhysRevB.99.214510 (DOI)000473009200002 ()2-s2.0-85068618863 (Scopus ID)
Available from: 2019-08-17 Created: 2019-08-17 Last updated: 2022-11-02Bibliographically approved
Galin, M. A., Borodianskyi, I. A., Kurin, V. V., Shereshevskiy, I. A., Vdovicheva, N. K., Krasnov, V. M. & Klushin, A. M. (2018). Evidence of synchronization of large Josephson-junction arrays by traveling electromagnetic waves. Paper presented at 3rd International Conference “Terahertz and Microwave Radiation: Generation, Detection and Applications” (TERA-2018). EPJ Web of Conferences, 195, Article ID 02004.
Open this publication in new window or tab >>Evidence of synchronization of large Josephson-junction arrays by traveling electromagnetic waves
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2018 (English)In: EPJ Web of Conferences, E-ISSN 2100-014X, Vol. 195, article id 02004Article in journal (Refereed) Published
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-181232 (URN)10.1051/epjconf/201819502004 (DOI)
Conference
3rd International Conference “Terahertz and Microwave Radiation: Generation, Detection and Applications” (TERA-2018)
Available from: 2020-04-28 Created: 2020-04-28 Last updated: 2023-07-06Bibliographically approved
Kalenyuk, A. A., Pagliero, A., Borodianskyi, E. A., Kordyuk, A. A. & Krasnov, V. M. (2018). Phase-Sensitive Evidence for the Sign-Reversal s± Symmetry of the Order Parameter in an Iron-Pnictide Superconductor Using Nb/Ba1−xNaxFe2As2 Josephson Junctions. Physical Review Letters, 120(6), Article ID 067001.
Open this publication in new window or tab >>Phase-Sensitive Evidence for the Sign-Reversal s± Symmetry of the Order Parameter in an Iron-Pnictide Superconductor Using Nb/Ba1−xNaxFe2As2 Josephson Junctions
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2018 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 120, no 6, article id 067001Article in journal (Refereed) Published
Abstract [en]

Josephson current provides a phase-sensitive tool for probing the pairing symmetry. Here we present an experimental study of high-quality Josephson junctions between a conventional s-wave superconductor Nb and a multiband iron-pnictide Ba1−xNaxFe2As2. Junctions exhibit a large enough critical current density to preclude the d-wave symmetry of the order parameter in the pnictide. However, the IcRn product is very small ≃3μV, which is not consistent with the sign-preserving s++ symmetry either. We argue that the small IcRn value, along with its unusual temperature dependence, provides evidence for the sign-reversal s± symmetry of the order parameter in Ba1−xNaxFe2As2. We conclude that it is the phase sensitivity of our junctions that leads to an almost complete (below a subpercent) cancellation of supercurrents from sign-reversal bands in the pnictide.

Keywords
Unconventional superconductivity, Tunneling, Josephson effect
National Category
Condensed Matter Physics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-153780 (URN)10.1103/PhysRevLett.120.067001 (DOI)000424193100011 ()29481253 (PubMedID)2-s2.0-85041822231 (Scopus ID)
Available from: 2018-03-20 Created: 2018-03-20 Last updated: 2022-10-25Bibliographically approved
Galin, M. A., Borodianskyi, E. A., Kurin, V. V., Shereshevskiy, I. A., Vdovicheva, N. K., Krasnov, V. M. & Klushin, A. M. (2018). Synchronization of Large Josephson-Junction Arrays by Traveling Electromagnetic Waves. Physical Review Applied, 9(5), Article ID 054032.
Open this publication in new window or tab >>Synchronization of Large Josephson-Junction Arrays by Traveling Electromagnetic Waves
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2018 (English)In: Physical Review Applied, E-ISSN 2331-7019, Vol. 9, no 5, article id 054032Article in journal (Refereed) Published
Abstract [en]

Mutual synchronization of many Josephson junctions is required for superradiant enhancement of the emission power. However, the larger the junction array is, the more difficult is the synchronization, especially when the array size becomes much larger than the emitted wavelength. Here, we study experimentally Josephson emission from such larger-than-the-wavelength Nb/NbSi/Nb junction arrays. For one of the arrays we observe a clear superradiant enhancement of emission above a threshold number of active junctions. The arrays exhibit strong geometrical resonances, seen as steps in current-voltage characteristics. However, radiation patterns of the arrays have forward-backward asymmetry, which is inconsistent with the solely geometrical resonance (standing-wave) mechanism of synchronization. We argue that the asymmetry provides evidence for an alternative mechanism of synchronization mediated by unidirectional traveling-wave propagation along the array (such as a surface plasmon). In this case, emission occurs predominantly in the direction of propagation of the traveling wave. Our conclusions are supported by numerical modeling of Josephson traveling-wave antenna. We argue that such a nonresonant mechanism of synchronization opens a possibility for phase locking of very large arrays of oscillators.

Keywords
Josephson junction arrays, coherent THz sources, Synchronization
National Category
Condensed Matter Physics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-157734 (URN)10.1103/PhysRevApplied.9.054032 (DOI)000433041700002 ()2-s2.0-85047735487 (Scopus ID)
Available from: 2018-08-03 Created: 2018-08-03 Last updated: 2022-10-26Bibliographically approved
Borodianskyi, E. A. & Krasnov, V. M. (2017). Josephson emission with frequency span 1–11 THz from small Bi2Sr2CaCu2O8+δ mesa structures. Nature Communications, 8, Article ID 1742.
Open this publication in new window or tab >>Josephson emission with frequency span 1–11 THz from small Bi2Sr2CaCu2O8+δ mesa structures
2017 (English)In: Nature Communications, E-ISSN 2041-1723, Vol. 8, article id 1742Article in journal (Refereed) Published
Abstract [en]

Mesa structures made of Bi2Sr2CaCu2O8+δ high-temperature superconductor represent stacks of atomic scale intrinsic Josephson junctions. They can be used for generation of high-frequency electromagnetic waves. Here we analyze Josephson emission from small-but-high mesas (with a small area, but containing many stacked junctions). We have found strong evidence for tunable terahertz emission with a good efficacy in a record high-frequency span 1–11 THz, approaching the theoretical upper limit for this superconductor. Emission maxima correspond to in-phase cavity modes in the mesas, indicating coherent superradiant nature of the emission. We conclude that terahertz emission requires a threshold number of junctions N ~ 100. The threshold behavior is not present in the classical description of stacked Josephson junctions and suggests importance of laser-like cascade amplification of the photon number in the cavity. 

National Category
Condensed Matter Physics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-149974 (URN)10.1038/s41467-017-01888-4 (DOI)000416229300028 ()29170380 (PubMedID)2-s2.0-85035045188 (Scopus ID)
Funder
Swedish Research Council, 621-2014-4314The Swedish Foundation for International Cooperation in Research and Higher Education (STINT), IG2013-5453
Available from: 2017-12-29 Created: 2017-12-29 Last updated: 2023-03-28Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-4815-5856

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