Special Issue "Superconductivity in Nanoscaled Systems"

A special issue of Nanomaterials (ISSN 2079-4991).

Deadline for manuscript submissions: closed (19 March 2021).

Special Issue Editor

Dr. Evgueni F. Talantsev
E-Mail Website1 Website2
Guest Editor
1. M.N. Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18, S. Kovalevskoy St., 620108 Ekaterinburg, Russia
2. NANOTECH Centre, Ural Federal University, 19 Mira St., 620002 Ekaterinburg, Russia
Interests: fundamentals of conventional and unconventional superconductivity; hydrogen-rich superconductors; 2D intrinsic and proximity-induced superconductivity; nanoscaled ferroelectric materials; shock-wave phsyics and applications; practical iron-based and cuprate superconductors
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Special Issue Information

Dear Colleagues,                

Within the last five years, experimental discoveries of intrinsic superconductivity in high-entropy alloys, highly-compressed hydrides, quasicrystals, approximant crystals, few layer stanene, and magic-angle twisted Dirac-cone materials have heralded a new era in this nearly 110-year-old field of science and technology. All these discoveries are associated with newly created/developed nanomaterials. This Special Issue aims to cover the latest aspects of these discoveries encompassing their fundamental understanding, basic properties, synthesis and fabrication routes, device methods, first-principles calculations, and other related topics. The format of welcomed articles includes full papers, communications, and reviews. Potential topics include but are not limited to:  

  1. First-principles exploration of hydrogen-rich superconductors;
  2. Experimental discoveries in highly-compressed hydrides;
  3. Superconductivity in magic-angles twisted 2D nanosheets;
  4. Experimental and theoretical studies of high-entropy alloys superconductors;
  5. Theory and experiment in superconducting quasicrystals and approximant crystals;
  6. Enhanced superconductivity in 2D and 1D limits;
  7. Hybrids nanoscaled ferroelectric/superconducting nanoscaled systems.

Accepted papers are published in the joint Special Issue in Nanomaterials or Nanomanufacturing (https://0-www-mdpi-com.brum.beds.ac.uk/journal/nanomanufacturing/special_issues/superconductivity_nano).

Dr. Evgueni F. Talantsev
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Magic-angle twisted 2D nanosheets
  • Hydrogen-rich superconductors
  • High-entropy alloys
  • Superconductivity in quasicrystals and approximant crystals
  • Enhanced superconductivity in 2D and 1D limits
  • Proximity-induced superconductivity in nanoscaled systems

Published Papers (12 papers)

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Research

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Article
Finite-Frequency Dissipation in Two-Dimensional Superconductors with Disorder at the Nanoscale
Nanomaterials 2021, 11(8), 1888; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11081888 - 23 Jul 2021
Viewed by 433
Abstract
Two-dimensional superconductors with disorder at the nanoscale can host a variety of intriguing phenomena. The superconducting transition is marked by a broad percolative transition with a long tail of the resistivity as function of the temperature. The fragile filamentary superconducting clusters, forming at [...] Read more.
Two-dimensional superconductors with disorder at the nanoscale can host a variety of intriguing phenomena. The superconducting transition is marked by a broad percolative transition with a long tail of the resistivity as function of the temperature. The fragile filamentary superconducting clusters, forming at low temperature, can be strengthened further by proximity effect with the surrounding metallic background, leading to an enhancement of the superfluid stiffness well below the percolative transition. Finite-frequency dissipation effects, e.g., related to the appearance of thermally excited vortices, can also significantly contribute to the resulting physics. Here, we propose a random impedance model to investigate the role of dissipation effects in the formation and strengthening of fragile superconducting clusters, discussing the solution within the effective medium theory. Full article
(This article belongs to the Special Issue Superconductivity in Nanoscaled Systems)
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Article
Quantifying the Charge Carrier Interaction in Metallic Twisted Bilayer Graphene Superlattices
Nanomaterials 2021, 11(5), 1306; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11051306 - 15 May 2021
Cited by 2 | Viewed by 777
Abstract
The mechanism of charge carrier interaction in twisted bilayer graphene (TBG) remains an unresolved problem, where some researchers proposed the dominance of the electron–phonon interaction, while the others showed evidence for electron–electron or electron–magnon interactions. Here we propose to resolve this problem by [...] Read more.
The mechanism of charge carrier interaction in twisted bilayer graphene (TBG) remains an unresolved problem, where some researchers proposed the dominance of the electron–phonon interaction, while the others showed evidence for electron–electron or electron–magnon interactions. Here we propose to resolve this problem by generalizing the Bloch–Grüneisen equation and using it for the analysis of the temperature dependent resistivity in TBG. It is a well-established theoretical result that the Bloch–Grüneisen equation power-law exponent, p, exhibits exact integer values for certain mechanisms. For instance, p = 5 implies the electron–phonon interaction, p = 3 is associated with the electron–magnon interaction and p = 2 applies to the electron–electron interaction. Here we interpret the linear temperature-dependent resistance, widely observed in TBG, as p1, which implies the quasielastic charge interaction with acoustic phonons. Thus, we fitted TBG resistance curves to the Bloch–Grüneisen equation, where we propose that p is a free-fitting parameter. We found that TBGs have a smoothly varied p-value (ranging from 1.4 to 4.4) depending on the Moiré superlattice constant, λ, or the charge carrier concentration, n. This implies that different mechanisms of the charge carrier interaction in TBG superlattices smoothly transition from one mechanism to another depending on, at least, λ and n. The proposed generalized Bloch–Grüneisen equation is applicable to a wide range of disciplines, including superconductivity and geology. Full article
(This article belongs to the Special Issue Superconductivity in Nanoscaled Systems)
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Article
Relationship between the TC of Smart Meta-Superconductor Bi(Pb)SrCaCuO and Inhomogeneous Phase Content
Nanomaterials 2021, 11(5), 1061; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11051061 - 21 Apr 2021
Cited by 1 | Viewed by 537
Abstract
A smart meta-superconductor Bi(Pb)SrCaCuO (B(P)SCCO) may increase the critical transition temperature (TC) of B(P)SCCO by electroluminescence (EL) energy injection of inhomogeneous phases. However, the increase amplitude ΔTC ( [...] Read more.
A smart meta-superconductor Bi(Pb)SrCaCuO (B(P)SCCO) may increase the critical transition temperature (TC) of B(P)SCCO by electroluminescence (EL) energy injection of inhomogeneous phases. However, the increase amplitude ΔTC (ΔTC=TCTC,pure) of TC is relatively small. In this study, a smart meta-superconductor B(P)SCCO with different matrix sizes was designed. Three kinds of raw materials with different particle sizes were used, and different series of Y2O3:Sm3+, Y2O3, Y2O3:Eu3+, and Y2O3:Eu3++Ag-doped samples and pure B(P)SCCO were prepared. Results indicated that the TC of the Y2O3 or Y2O3:Sm3+ non-luminescent dopant doping sample is lower than that of pure B(P)SCCO. However, the TC of the Y2O3:Eu3++Ag or Y2O3:Eu3+ luminescent inhomogeneous phase doping sample is higher than that of pure B(P)SCCO. With the decrease of the raw material particle size from 30 to 5 μm, the particle size of the B(P)SCCO superconducting matrix in the prepared samples decreases, and the doping content of the Y2O3:Eu3++Ag or Y2O3:Eu3+ increases from 0.2% to 0.4%. Meanwhile, the increase of the inhomogeneous phase content enhances the ΔTC. When the particle size of raw material is 5 μm, the doping concentration of the luminescent inhomogeneous phase can be increased to 0.4%. At this time, the zero-resistance temperature and onset transition temperature of the Y2O3:Eu3++Ag doped sample are 4 and 6.3 K higher than those of pure B(P)SCCO, respectively. Full article
(This article belongs to the Special Issue Superconductivity in Nanoscaled Systems)
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Article
Nanoscale Superconducting States in the Fe-Based Filamentary Superconductor of Pr-Doped CaFe2As2
Nanomaterials 2021, 11(4), 1019; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11041019 - 16 Apr 2021
Viewed by 454
Abstract
The low-temperature scanning tunneling microscope and spectroscopy (STM/STS) are used to visualize superconducting states in the cleaved single crystal of 9% praseodymium-doped CaFe2As2 (Pr-Ca122) with Tc ≈ 30 K. The spectroscopy shows strong spatial variations in the density of [...] Read more.
The low-temperature scanning tunneling microscope and spectroscopy (STM/STS) are used to visualize superconducting states in the cleaved single crystal of 9% praseodymium-doped CaFe2As2 (Pr-Ca122) with Tc ≈ 30 K. The spectroscopy shows strong spatial variations in the density of states (DOS), and the superconducting map constructed from spectroscopy discloses a localized superconducting phase, as small as a single unit cell. The comparison of the spectra taken at 4.2 K and 22 K (below vs. close to the bulk superconducting transition temperature) from the exact same area confirms the superconducting behavior. Nanoscale superconducting states have been found near Pr dopants, which can be identified using dI/dV conductance maps at +300 mV. There is no correlation of the local superconductivity to the surface reconstruction domain and surface defects, which reflects its intrinsic bulk behavior. We, therefore, suggest that the local strain of Pr dopants is competing with defects induced local magnetic moments; this competition is responsible for the local superconducting states observed in this Fe-based filamentary superconductor. Full article
(This article belongs to the Special Issue Superconductivity in Nanoscaled Systems)
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Article
Supercurrent Induced by Chiral Coupling in Multiferroic/Superconductor Nanostructures
Nanomaterials 2021, 11(1), 184; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11010184 - 13 Jan 2021
Cited by 1 | Viewed by 570
Abstract
We study the transport and the superconducting dynamics in a layer of type II superconductor (SC) with a normal top layer that hosts a helical magnetic ordering that gives rise to spin-current-driven ferroelectric polarization. Proximity effects akin to this heterostructure result in an [...] Read more.
We study the transport and the superconducting dynamics in a layer of type II superconductor (SC) with a normal top layer that hosts a helical magnetic ordering that gives rise to spin-current-driven ferroelectric polarization. Proximity effects akin to this heterostructure result in an anisotropic supercurrent transport and modify the dynamic properties of vortices in the SC. The vortices can be acted upon and controlled by electric gating or other means that couple to the spin ordering in the top layer, which, in turn, alter the superconducting/helical magnet coupling characteristics. We demonstrate, using the time dependent Ginzburg–Landau approach, how the spin helicity of the top layer can be utilized for pinning and guiding the vortices in the superconducting layer. Full article
(This article belongs to the Special Issue Superconductivity in Nanoscaled Systems)
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Article
Simplicity Out of Complexity: Band Structure for W20O58 Superconductor
Nanomaterials 2021, 11(1), 97; https://doi.org/10.3390/nano11010097 - 04 Jan 2021
Cited by 1 | Viewed by 568
Abstract
The band structure, density of states, and the Fermi surface of a recently discovered superconductor, oxygen-deficient tungsten oxide WO2.9 that is equivalent to W20O58, is studied within the density functional theory (DFT) in the generalized gradient approximation (GGA). [...] Read more.
The band structure, density of states, and the Fermi surface of a recently discovered superconductor, oxygen-deficient tungsten oxide WO2.9 that is equivalent to W20O58, is studied within the density functional theory (DFT) in the generalized gradient approximation (GGA). Here we show that despite the extremely complicated structure containing 78 atoms in the unit cell, the low-energy band structure is quite feasible. Fermi level is crossed by no more than 10 bands per one spin projection (and even 9 bands per pseudospin projection when the spin-orbit coupling is considered) originating from the t2g 5d-orbitals of tungsten atoms forming zigzag chains. These bands become occupied because of the specific zigzag octahedra distortions. To demonstrate the role of distortions, we compare band structures of W20O58 with the real crystal structure and with the idealized one. We also propose a basis for a minimal low-energy tight-binding model for W20O58. Full article
(This article belongs to the Special Issue Superconductivity in Nanoscaled Systems)
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Article
Quantum Interference and Nonequilibrium Josephson Currents in Molecular Andreev Interferometers
Nanomaterials 2020, 10(6), 1033; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10061033 - 28 May 2020
Viewed by 1035
Abstract
We study the quantum interference (QI) effects in three-terminal Andreev interferometers based on polyaromatic hydrocarbons (PAHs) under non-equilibrium conditions. The Andreev interferometer consists of a PAH coupled to two superconducting and one normal conducting terminals. We calculate the current measured in the normal [...] Read more.
We study the quantum interference (QI) effects in three-terminal Andreev interferometers based on polyaromatic hydrocarbons (PAHs) under non-equilibrium conditions. The Andreev interferometer consists of a PAH coupled to two superconducting and one normal conducting terminals. We calculate the current measured in the normal lead as well as the current between the superconducting terminals under non-equilibrium conditions. We show that both the QI arising in the PAH cores and the bias voltage applied to a normal contact have a fundamental effect on the charge distribution associated with the Andreev Bound States (ABSs). QI can lead to a peculiar dependence of the normal current on the superconducting phase difference that was not observed in earlier studies of mesoscopic Andreev interferometers. We explain our results by an induced asymmetry in the spatial distribution of the electron- and hole-like quasiparticles. The non-equilibrium charge occupation induced in the central PAH core can result in a π transition in the current-phase relation of the supercurrent for large enough applied bias voltage on the normal lead. The asymmetry in the spatial distribution of the electron- and hole-like quasiparticles might be used to split Cooper pairs and hence to produce entangled electrons in four terminal setups. Full article
(This article belongs to the Special Issue Superconductivity in Nanoscaled Systems)
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Article
Enhancement of Superconductivity by Amorphizing Molybdenum Silicide Films Using a Focused Ion Beam
Nanomaterials 2020, 10(5), 950; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10050950 - 16 May 2020
Cited by 2 | Viewed by 1178
Abstract
We have used focused ion beam irradiation to progressively cause defects in annealed molybdenum silicide thin films. Without the treatment, the films are superconducting with critical temperature of about 1 K. We observe that both resistivity and critical temperature increase as the ion [...] Read more.
We have used focused ion beam irradiation to progressively cause defects in annealed molybdenum silicide thin films. Without the treatment, the films are superconducting with critical temperature of about 1 K. We observe that both resistivity and critical temperature increase as the ion dose is increased. For resistivity, the increase is almost linear, whereas critical temperature changes abruptly at the smallest doses and then remains almost constant at 4 K. We believe that our results originate from amorphization of the polycrystalline molybdenum silicide films. Full article
(This article belongs to the Special Issue Superconductivity in Nanoscaled Systems)
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Article
Induced Topological Superconductivity in a BiSbTeSe2-Based Josephson Junction
Nanomaterials 2020, 10(4), 794; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10040794 - 21 Apr 2020
Cited by 3 | Viewed by 1430
Abstract
A 4π-periodic supercurrent through a Josephson junction can be a consequence of the presence of Majorana bound states. A systematic study of the radio frequency response for several temperatures and frequencies yields a concrete protocol for examining the 4π-periodic [...] Read more.
A 4 π -periodic supercurrent through a Josephson junction can be a consequence of the presence of Majorana bound states. A systematic study of the radio frequency response for several temperatures and frequencies yields a concrete protocol for examining the 4 π -periodic contribution to the supercurrent. This work also reports the observation of a 4 π -periodic contribution to the supercurrent in BiSbTeSe 2 -based Josephson junctions. As a response to irradiation by radio frequency waves, the junctions showed an absence of the first Shapiro step. At high irradiation power, a qualitative correspondence to a model including a 4 π -periodic component to the supercurrent is found. Full article
(This article belongs to the Special Issue Superconductivity in Nanoscaled Systems)
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Article
DC Self-Field Critical Current in Superconductor/Dirac-Cone Material/Superconductor Junctions
Nanomaterials 2019, 9(11), 1554; https://0-doi-org.brum.beds.ac.uk/10.3390/nano9111554 - 01 Nov 2019
Cited by 2 | Viewed by 1570
Abstract
Recently, several research groups have reported on anomalous enhancement of the self-field critical currents, Ic(sf,T), at low temperatures in superconductor/Dirac-cone material/superconductor (S/DCM/S) junctions. Some papers attributed the enhancement to the low-energy Andreev bound states arising from winding of the [...] Read more.
Recently, several research groups have reported on anomalous enhancement of the self-field critical currents, Ic(sf,T), at low temperatures in superconductor/Dirac-cone material/superconductor (S/DCM/S) junctions. Some papers attributed the enhancement to the low-energy Andreev bound states arising from winding of the electronic wave function around DCM. In this paper, Ic(sf,T) in S/DCM/S junctions have been analyzed by two approaches: modified Ambegaokar-Baratoff and ballistic Titov-Beenakker models. It is shown that the ballistic model, which is traditionally considered to be a basic model to describe Ic(sf,T) in S/DCM/S junctions, is an inadequate tool to analyze experimental data from these type of junctions, while Ambegaokar-Baratoff model, which is generally considered to be a model for Ic(sf,T) in superconductor/insulator/superconductor junctions, provides good experimental data description. Thus, there is a need to develop a new model for self-field critical currents in S/DCM/S systems. Full article
(This article belongs to the Special Issue Superconductivity in Nanoscaled Systems)
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Review

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Review
Nanosized Pinning Centers in the Rare Earth-Barium-Copper-Oxide Thin-Film Superconductors
Nanomaterials 2020, 10(8), 1429; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10081429 - 22 Jul 2020
Cited by 4 | Viewed by 1283
Abstract
Since the discovery of high-temperature superconductivity, significant progress in the fabrication of REBCO-based (Rare Earth Barium Copper mixed Oxides) thin-films superconductors has been achieved. In our review, we described the approaches and possibilities of the improvement of superconducting properties by the introduction of [...] Read more.
Since the discovery of high-temperature superconductivity, significant progress in the fabrication of REBCO-based (Rare Earth Barium Copper mixed Oxides) thin-films superconductors has been achieved. In our review, we described the approaches and possibilities of the improvement of superconducting properties by the introduction of nanosized pinning centers. We focused on the synthesis and viability of the material for artificial pinning centers and methods used for the introduction of the pinning centers into superconducting REBCO-based thin-films. This article summarizes available materials and procedures regardless of the financial cost of the individual method. According to available literature, the most significant superconducting REBCO tapes can be obtained when a combination of 1D and 0D nanoparticles are used for nanoscale pinning. Full article
(This article belongs to the Special Issue Superconductivity in Nanoscaled Systems)
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Review
Unconventional Applications of Superconducting Nanowire Single Photon Detectors
Nanomaterials 2020, 10(6), 1198; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10061198 - 19 Jun 2020
Cited by 5 | Viewed by 1610
Abstract
Superconducting nanowire single photon detectors are becoming a dominant technology in quantum optics and quantum communication, primarily because of their low timing jitter and capability to detect individual low-energy photons with high quantum efficiencies. However, other desirable characteristics, such as high detection rates, [...] Read more.
Superconducting nanowire single photon detectors are becoming a dominant technology in quantum optics and quantum communication, primarily because of their low timing jitter and capability to detect individual low-energy photons with high quantum efficiencies. However, other desirable characteristics, such as high detection rates, operation in cryogenic and high magnetic field environments, or high-efficiency detection of charged particles, are underrepresented in literature, potentially leading to a lack of interest in other fields that might benefit from this technology. We review the progress in use of superconducting nanowire technology in photon and particle detection outside of the usual areas of physics, with emphasis on the potential use in ongoing and future experiments in nuclear and high energy physics. Full article
(This article belongs to the Special Issue Superconductivity in Nanoscaled Systems)
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