Special Issue "Metallic Superconductors - The Workhorses of Superconductivity"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: 10 August 2020.

Special Issue Editor

Prof. Dr. Michael Koblischka
Website
Guest Editor
Department of Materials Science and Engineering, Shibaura Institute of Technology 3‐7‐5 Toyosu, Koto‐ku, Tokyo, Japan
Interests: Superconductors; Bulk superconductor magnets; Magnetic imaging; Magnetic recording

Special Issue Information

Dear Colleagues,

Superconductivity was first discovered in metal superconductors, and the first real applications brought up by the first intermetallic alloys still play an important role until now (NbTi, Nb3Sn). Moreover, the development of MgB2 which reaches the highest superconducting transition temperature of approx. 38 K (without external pressure) enables new research possibilities for applications at ~20 K provided by cryo-cooling systems. MgB2 can replace high-Tc superconductor-based materials due to the fact that a relatively cheap manufacturing process is possible to be applied, and there are no (expensive) rare-earth materials involved. However, MgB2 shares many features with previous materials like Nb3Sn. The ever present quest for higher critical currents requires intense research concerning the flux pinning sites created artificially (mechanical deformation or chemical doping), by irradiation and newly developed processing techniques.

Another interesting aspect of metallic superconductors is that they still provide new insights to superconductivity, both theoretically and experimentally. Among such observations is the paramagnetic Meissner effect (PME) observed firstly in Nb disks, and since then also in other metallic systems. Further, two-dimensional systems based on metallic materials like NbSe2, Bi2Te3, etc. offer a simple experimental access to these systems. Therefore, the research on metallic superconductors still offers many possibilities and new developments.

Prof. Dr. Michael Koblischka
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. Metals 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 1600 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

  • Artificial pinning centers (APC)
  • Critical currents, flux pinning
  • Flux jumps
  • Rare-earth free superconductors
  • Trapped field magnets
  • Sparc plasma sintering
  • CVD growth
  • 2D materials
  • Topological superconductors
  • Paramagnetic Meissner effect
  • Magnetic imaging of flux structures

Published Papers (3 papers)

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Research

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Open AccessFeature PaperArticle
Relation between Crystal Structure and Transition Temperature of Superconducting Metals and Alloys
Metals 2020, 10(2), 158; https://doi.org/10.3390/met10020158 - 21 Jan 2020
Abstract
Using the Roeser–Huber equation, which was originally developed for high temperature superconductors (HTSc) (H. Roeser et al., Acta Astronautica 62 (2008) 733), we present a calculation of the superconducting transition temperatures, T c , of some elements with fcc unit cells (Pb, Al), [...] Read more.
Using the Roeser–Huber equation, which was originally developed for high temperature superconductors (HTSc) (H. Roeser et al., Acta Astronautica 62 (2008) 733), we present a calculation of the superconducting transition temperatures, T c , of some elements with fcc unit cells (Pb, Al), some elements with bcc unit cells (Nb, V), Sn with a tetragonal unit cell and several simple metallic alloys (NbN, NbTi, the A15 compounds and MgB 2 ). All calculations used only the crystallographic information and available data of the electronic configuration of the constituents. The model itself is based on viewing superconductivity as a resonance effect, and the superconducting charge carriers moving through the crystal interact with a typical crystal distance, x. It is found that all calculated T c -data fall within a narrow error margin on a straight line when plotting ( 2 x ) 2 vs. 1 / T c like in the case for HTSc. Furthermore, we discuss the problems when obtaining data for T c from the literature or from experiments, which are needed for comparison with the calculated data. The T c -data presented here agree reasonably well with the literature data. Full article
(This article belongs to the Special Issue Metallic Superconductors - The Workhorses of Superconductivity)
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Review

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Open AccessReview
Magnetic Recording of Superconducting States
Metals 2019, 9(10), 1022; https://doi.org/10.3390/met9101022 - 20 Sep 2019
Cited by 2
Abstract
Local polarization of magnetic materials has become a well-known and widely used method for storing binary information. Numerous applications in our daily life such as credit cards, computer hard drives, and the popular magnetic drawing board toy, rely on this principle. In this [...] Read more.
Local polarization of magnetic materials has become a well-known and widely used method for storing binary information. Numerous applications in our daily life such as credit cards, computer hard drives, and the popular magnetic drawing board toy, rely on this principle. In this work, we review the recent advances on the magnetic recording of inhomogeneous magnetic landscapes produced by superconducting films. We summarize the current compelling experimental evidence showing that magnetic recording can be applied for imprinting in a soft magnetic layer the flux trajectory taking place in a superconducting layer at cryogenic temperatures. This approach enables the ex-situ observation at room temperature of the imprinted magnetic flux landscape obtained below the critical temperature of the superconducting state. The undeniable appeal of the proposed technique lies in its simplicity and the potential to improve the spatial resolution, possibly down to the scale of a few vortices. Full article
(This article belongs to the Special Issue Metallic Superconductors - The Workhorses of Superconductivity)
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Open AccessFeature PaperReview
The Path to Type-II Superconductivity
Metals 2019, 9(6), 682; https://doi.org/10.3390/met9060682 - 14 Jun 2019
Abstract
Following the discovery of superconductivity by Heike Kamerlingh Onnes in 1911, research concentrated on the electric conductivity of the materials investigated. Then, it was Max von Laue who in the early 1930s turned his attention to the magnetic properties of superconductors, such as [...] Read more.
Following the discovery of superconductivity by Heike Kamerlingh Onnes in 1911, research concentrated on the electric conductivity of the materials investigated. Then, it was Max von Laue who in the early 1930s turned his attention to the magnetic properties of superconductors, such as their demagnetizing effects in a weak magnetic field. As a consultant at the Physikalisch-Technische Reichsanstalt in Berlin, von Laue was in close contact with Walther Meissner at the Reichsanstalt. In 1933, Meisner together with Robert Ochsenfeld discovered the perfect diamagnetism of superconductors (Meissner–Ochsenfeld effect). This was a turning point, indicating that superconductivity represents a thermodynamic equilibrium state and leading to the London theory and the Ginzburg–Landau theory. In the early 1950s in Moscow, Nikolay Zavaritzkii carried out experiments on superconducting thin films. In the theoretical analysis of his experiments, he collaborated with Alexei A. Abrikosov and for the first time they considered the possibility that the coherence length ξ can be smaller than the magnetic penetration depth λ m . They called these materials the “second group”. Subsequently, Abrikosov discovered the famous Abrikosov vortex lattice and the superconducting mixed state. The important new field of type-II superconductivity was born. Full article
(This article belongs to the Special Issue Metallic Superconductors - The Workhorses of Superconductivity)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Article Type: Review
Article Title: Magnetic recording of superconducting states
Author: Prof. Alejandro V. Silhanek

Article Type: Review
Article Title: Review of the paramagnetic Meissner effect (PME) in metallic superconductors
Author: Prof. Dr. Michael Koblischka

Article Type: Article
Article Title: Ternary Molybdenum Chalcogenide superconducting wires
Author: Dr. B. Seeber

Abstract: 

Ternary Molybdenum Chalcogenide (TMC) superconducting wires were intensely studied worldwide before the discovery of High Temperature Superconductors (HTS). TMCs are Low Temperature Superconductors (LTS) with a critical temperature up to 15 K and upper critical fields in the range of 50 T @ 4.2 K, e.g. the compound PbMo6S8. This is more than twice of Nb3Sn. However, the most important feature of TMCs is the combination of a small field dependence of the critical current (< 40 T) and the low price of raw materials. Then a TMC superconducting wire may be cost efficient above 5 T and 12 T with respect to NbTi and Nb3Sn, respectively. In comparison to HTS, TMC is about one order of magnitude less expensive and many physical properties, important for applications, are superior. Up to now TMCs suffers under of a not sufficient critical current density, Jc. In this contribution aspects regarding an improvement of Jc of TMC conductors are discussed. According an experimentally observed master scaling curve for the pinning force vs. magnetic field, a prospective critical current density can be calculated. The result is confirmed by an independent Jc measurement of a high quality TMC bulk sample. It is expected that a new manufacturing process of TMC wires (US and European patents are granted recently) will substantially improve the critical current density. TMC wires don’t need a reaction heat treatment like Nb3Sn wires and can be wound into a magnet almost like NbTi. Together with cost considerations, this paves the way for a next generation superconductor.

 

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