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Shimizu M, Takemori N, Guterding D, Jeschke HO. Two-Dome Superconductivity in FeS Induced by a Lifshitz Transition. Phys Rev Lett 2018; 121:137001. [PMID: 30312064 DOI: 10.1103/physrevlett.121.137001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Indexed: 06/08/2023]
Abstract
Among iron chalcogenide superconductors, FeS can be viewed as a simple, highly compressed relative of FeSe without a nematic phase and with weaker electronic correlations. Under pressure, however, the superconductivity of stoichiometric FeS disappears and reappears, forming two domes. We perform electronic structure and spin fluctuation theory calculations for tetragonal FeS in order to analyze the nature of the superconducting order parameter. In the random phase approximation, we find a gap function with d-wave symmetry at ambient pressure, in agreement with several reports of a nodal superconducting order parameter in FeS. Our calculations show that, as a function of pressure, the superconducting pairing strength decreases until a Lifshitz transition takes place at 4.6 GPa. As a hole pocket with a large density of states appears at the Lifshitz transition, the gap symmetry is altered to sign-changing s wave. At the same time, the pairing strength is severely enhanced and increases up to a new maximum at 5.5 GPa. Therefore, our calculations naturally explain the occurrence of two superconducting domes in FeS.
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Affiliation(s)
- Makoto Shimizu
- Department of Physics, Okayama University, Okayama 700-8530, Japan
| | - Nayuta Takemori
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Daniel Guterding
- Fachbereich Mathematik, Naturwissenschaften und Datenverarbeitung, Technische Hochschule Mittelhessen, Wilhelm-Leuschner-Straße 13, 61169 Friedberg, Germany
| | - Harald O Jeschke
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
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Guterding D, Jeschke HO, Mazin II, Glasbrenner JK, Bascones E, Valentí R. Nontrivial Role of Interlayer Cation States in Iron-Based Superconductors. Phys Rev Lett 2017; 118:017204. [PMID: 28106450 DOI: 10.1103/physrevlett.118.017204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Indexed: 06/06/2023]
Abstract
Unconventional superconductivity in iron pnictides and chalcogenides has been suggested to be controlled by the interplay of low-energy antiferromagnetic spin fluctuations and the particular topology of the Fermi surface in these materials. Based on this premise, one would also expect the large class of isostructural and isoelectronic iron germanide compounds to be good superconductors. As a matter of fact, they, however, superconduct at very low temperatures or not at all. In this work we establish that superconductivity in iron germanides is suppressed by strong ferromagnetic tendencies, which surprisingly do not originate from changes in bond angles or bond distances with respect to iron pnictides and chalcogenides, but are due to changes in the electronic structure in a wide range of energies happening upon substitution of atom species (As by Ge and the corresponding spacer cations). Our results indicate that superconductivity in iron-based materials may not always be fully understood based on d or d-p model Hamiltonians only.
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Affiliation(s)
- Daniel Guterding
- Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
| | - Harald O Jeschke
- Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
| | - I I Mazin
- Code 6393, Naval Research Laboratory, Washington, District of Columbia 20375, USA
| | - J K Glasbrenner
- National Research Council/Code 6393, Naval Research Laboratory, Washington, District of Columbia 20375, USA
| | - E Bascones
- Instituto de Ciencia de Materiales de Madrid, ICMM-CSIC, Cantoblanco, 28049 Madrid, Spain
| | - Roser Valentí
- Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
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Guterding D, Diehl S, Altmeyer M, Methfessel T, Tutsch U, Schubert H, Lang M, Müller J, Huth M, Jeschke HO, Valentí R, Jourdan M, Elmers HJ. Evidence for Eight-Node Mixed-Symmetry Superconductivity in a Correlated Organic Metal. Phys Rev Lett 2016; 116:237001. [PMID: 27341250 DOI: 10.1103/physrevlett.116.237001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Indexed: 06/06/2023]
Abstract
We report on a combined theoretical and experimental investigation of the superconducting state in the quasi-two-dimensional organic superconductor κ-(ET)_{2}Cu[N(CN)_{2}]Br. Applying spin-fluctuation theory to a low-energy, material-specific Hamiltonian derived from ab initio density functional theory we calculate the quasiparticle density of states in the superconducting state. We find a distinct three-peak structure that results from a strongly anisotropic mixed-symmetry superconducting gap with eight nodes and twofold rotational symmetry. This theoretical prediction is supported by low-temperature scanning tunneling spectroscopy on in situ cleaved single crystals of κ-(ET)_{2}Cu[N(CN)_{2}]Br with the tunneling direction parallel to the layered structure.
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Affiliation(s)
- Daniel Guterding
- Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main, Germany
| | - Sandra Diehl
- Graduate School Materials Science in Mainz, Staudingerweg 9, 55128 Mainz, Germany
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - Michaela Altmeyer
- Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main, Germany
| | - Torsten Methfessel
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - Ulrich Tutsch
- Physikalisches Institut, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main, Germany
| | - Harald Schubert
- Physikalisches Institut, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main, Germany
| | - Michael Lang
- Physikalisches Institut, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main, Germany
| | - Jens Müller
- Physikalisches Institut, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main, Germany
| | - Michael Huth
- Physikalisches Institut, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main, Germany
| | - Harald O Jeschke
- Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main, Germany
| | - Roser Valentí
- Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main, Germany
| | - Martin Jourdan
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - Hans-Joachim Elmers
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany
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