Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
5.4
2.2
Journals
Symmetry
Special Issues
Understanding Iron Superconductors and Isostructural Materials
share announcement

Understanding Iron Superconductors and Isostructural Materials

A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Chemistry: Symmetry/Asymmetry".

Deadline for manuscript submissions: closed (15 September 2022) | Viewed by 8537

Special Issue Editor

Dr. Daniil Evtushinsky

E-Mail Website
Guest Editor
Laboratory for Quantum Magnetism, Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
Interests: iron-based superconductors; Fermi surface shape; superconducting gap distribution; self-energy effects

Special Issue Information

Dear Colleagues,

Studies of iron-based superconductors, stimulated by an enormous public interest and supported by the experience collected from the preceding work on the unconventional superconductivity, have already instigated substantial progress in the field. It is possible to synthesize numerous related yet different materials of the iron family, and to perform their detailed investigation using powerful experimental and computational techniques. An assortment of spontaneous orders, related to the breaking of all possible symmetries of the many-electron wave function, has been detected in these materials. We have accumulated a good bulk of evidence suggesting that such proximity of different electronic phases is connected to the very origin of unconventional superconductivity. Nevertheless, the precise formulation of what actually underlies efficient electron pairing has not yet been achieved. Recently, compounds of the same crystalline symmetries, but with iron substituted by the other d elements, have caught the attention of the research community. Backed by a large number of relevant systems with behavior continuously varying in a wide range, studies of the prerequisites necessary for unconventional superconductivity to emerge are proceeding at full pace. 

This Special Issue will collect new experimental and theoretical results, as well as overviews, generalizations, and analyses of the known facts, facilitating the understanding of iron-based superconductors from a wide perspective.

Dr. Daniil Evtushinsky
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 submissions that pass pre-check are 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. Symmetry 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 2400 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

  • unconventional superconductivity
  • iron superconductors
  • electronic structure
  • correlated electronic systems
  • crystalline structure symmetry
  • transition metal compounds

Benefits of Publishing in a Special Issue

  • Ease of navigation: Grouping papers by topic helps scholars navigate broad scope journals more efficiently.
  • Greater discoverability: Special Issues support the reach and impact of scientific research. Articles in Special Issues are more discoverable and cited more frequently.
  • Expansion of research network: Special Issues facilitate connections among authors, fostering scientific collaborations.
  • External promotion: Articles in Special Issues are often promoted through the journal's social media, increasing their visibility.
  • e-Book format: Special Issues with more than 10 articles can be published as dedicated e-books, ensuring wide and rapid dissemination.

Further information on MDPI's Special Issue polices can be found here.

Published Papers (3 papers)

Download All Papers
Order results
Result details
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:

Research

15 pages, 435 KiB  
Article
Multiplicity, Parity and Angular Momentum of a Cooper Pair in Unconventional Superconductors of D4h Symmetry: Sr2RuO4 and Fe-Pnictide Materials
by Victor G. Yarzhemsky
Symmetry 2021, 13(8), 1435; https://doi.org/10.3390/sym13081435 - 5 Aug 2021
Cited by 3 | Viewed by 2169
Abstract
Sr2RuO4 and Fe-pnictide superconductors belong to the same point group symmetry D4h. Many experimental data confirm odd pairs in Sr2RuO4 and even pairs in Fe-pnictides, but opposite conclusions also exist. Recent NMR results of [...] Read more.
Sr2RuO4 and Fe-pnictide superconductors belong to the same point group symmetry D4h. Many experimental data confirm odd pairs in Sr2RuO4 and even pairs in Fe-pnictides, but opposite conclusions also exist. Recent NMR results of Pustogow et al., which revealed even Cooper pairs in Sr2RuO4, require reconsideration of symmetry treatment of its SOP (superconducting order parameter). In the present work making use of the Mackey–Bradley theorem on symmetrized squares, a group theoretical investigation of possible pairing states in D4h symmetry is performed. It is obtained for I4/mmm , i.e., space group of Sr2RuO4, that triplet pairs with even spatial parts are possible in kz direction and in points M and Y. For the two latter cases pairing of equivalent electrons with nonzero total momentum is proposed. In P4/nmm space group of Fe- pnictides in point M, even and odd pairs are possible for singlet and triplet cases. It it shown that even and odd chiral states with angular momentum projection m=±1 have nodes in vertical planes, but Eg is nodal , whereas Eu is nodeless in the basal plane. It is also shown that the widely accepted assertion that the parity of angular momentum value is directly connected with the spatial parity of a pair is not valid in a space-group approach to the wavefunction of a Cooper pair. Full article
(This article belongs to the Special Issue Understanding Iron Superconductors and Isostructural Materials)
►▼ Show Figures

Figure 1

16 pages, 762 KiB  
Article
Electronic Origin of Tc in Bulk and Monolayer FeSe
by Swagata Acharya, Dimitar Pashov, Francois Jamet and Mark van Schilfgaarde
Symmetry 2021, 13(2), 169; https://doi.org/10.3390/sym13020169 - 23 Jan 2021
Cited by 10 | Viewed by 3187
Abstract
FeSe is classed as a Hund’s metal, with a multiplicity of d bands near the Fermi level. Correlations in Hund’s metals mostly originate from the exchange parameter J, which can drive a strong orbital selectivity in the correlations. The Fe-chalcogens are the [...] Read more.
FeSe is classed as a Hund’s metal, with a multiplicity of d bands near the Fermi level. Correlations in Hund’s metals mostly originate from the exchange parameter J, which can drive a strong orbital selectivity in the correlations. The Fe-chalcogens are the most strongly correlated of the Fe-based superconductors, with dxy the most correlated orbital. Yet little is understood whether and how such correlations directly affect the superconducting instability in Hund’s systems. By applying a recently developed ab initio theory, we show explicitly the connections between correlations in dxy and the superconducting critical temperature Tc. Starting from the ab initio results as a reference, we consider various kinds of excursions in parameter space around the reference to determine what controls Tc. We show small excursions in J can cause colossal changes in Tc. Additionally we consider changes in hopping by varying the Fe-Se bond length in bulk, in the free standing monolayer M-FeSe, and M-FeSe on a SrTiO3 substrate (M-FeSe/STO). The twin conditions of proximity of the dxy state to the Fermi energy, and the strength of J emerge as the primary criteria for incoherent spectral response and enhanced single- and two-particle scattering that in turn controls Tc. Using c-RPA, we show further that FeSe in monolayer form (M-FeSe) provides a natural mechanism to enhance J. We explain why M-FeSe/STO has a high Tc, whereas M-FeSe in isolation should not. Our study opens a paradigm for a unified understanding what controls Tc in bulk, layers, and interfaces of Hund’s metals by hole pocket and electron screening cloud engineering. Full article
(This article belongs to the Special Issue Understanding Iron Superconductors and Isostructural Materials)
►▼ Show Figures

Figure 1

8 pages, 2142 KiB  
Article
Unusual Temperature Evolution of Quasiparticle Band Dispersion in Electron-Doped FeSe Films
by Kosuke Nakayama, Koshin Shigekawa, Katsuaki Sugawara, Takashi Takahashi and Takafumi Sato
Symmetry 2021, 13(2), 155; https://doi.org/10.3390/sym13020155 - 20 Jan 2021
Cited by 1 | Viewed by 2100
Abstract
The discovery of high-temperature (high-Tc) superconductivity in one-monolayer FeSe on SrTiO3 has attracted tremendous attention. Subsequent studies suggested the importance of cooperation between intra-FeSe-layer and interfacial interactions to enhance Tc. However, the nature of intra-FeSe-layer interactions, which [...] Read more.
The discovery of high-temperature (high-Tc) superconductivity in one-monolayer FeSe on SrTiO3 has attracted tremendous attention. Subsequent studies suggested the importance of cooperation between intra-FeSe-layer and interfacial interactions to enhance Tc. However, the nature of intra-FeSe-layer interactions, which would play a primary role in determining the pairing symmetry, remains unclear. Here we have performed high-resolution angle-resolved photoemission spectroscopy of one-monolayer and alkaline-metal-deposited multilayer FeSe films on SrTiO3, and determined the evolution of quasiparticle band dispersion across Tc. We found that the band dispersion in the superconducting state deviates from the Bogoliubov-quasiparticle dispersion expected from the normal-state band dispersion with a constant gap size. This suggests highly anisotropic pairing originating from small momentum transfer and/or mass renormalization due to electron–boson coupling. This band anomaly is interpreted in terms of the electronic interactions within the FeSe layers that may be related to the high-Tc superconductivity in electron-doped FeSe. Full article
(This article belongs to the Special Issue Understanding Iron Superconductors and Isostructural Materials)
►▼ Show Figures

Figure 1

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-3
Back to TopTop