Effects of Coulomb interactions on the superconducting gaps in iron-based superconductors

doi:https://doi.org/10.1103/PhysRevB.93.155159

Title: Effects of Coulomb interactions on the superconducting gaps in iron-based superconductors

Abstract

Recent angle-resolved photoemission spectroscopy measurements of Co-doped LiFeAs report a large and robust superconducting gap on the Γ-centered hole band that lies 8 meV below the Fermi level. We show that, unlike a conventional superconductor described by BCS theory, a multiband system with strong interband Coulomb interactions can explain these observations. We model LiFeAs with a five-band model in which the shallow hole band is coupled with the other bands by only Coulomb interactions. Using Eliashberg theory, we find reasonable interaction parameters that reproduce the T _c and all five gaps of LiFeAs. The energy independence of the Coulomb interactions then ensures the robustness of the gap induced on the shallow band. Furthermore, due to the repulsive nature of the Coulomb interactions, the gap changes sign between the shallow band and the other hole pockets, corresponding to an unconventional s _± gap symmetry. Unlike other families of iron-based superconductors, the gap symmetry of LiFeAs has not been ascertained experimentally. Finally, the experimental implications of this sign-changing state are discussed.

Authors:

Leong, Zhidong ^[1]; Phillips, Philip ^[1]

Univ. of Illinois at Urbana-Champaign, IL (United States)

Publication Date:: 2016-04-27

Research Org.:: Energy Frontier Research Centers (EFRC) (United States). Center for Emergent Superconductivity (CES)

Sponsoring Org.:: USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:: 1387865

Alternate Identifier(s):: OSTI ID: 1249945

Grant/Contract Number:: AC02-98CH10886

Resource Type:: Journal Article: Accepted Manuscript

Journal Name:: Physical Review B

Additional Journal Information:: Journal Volume: 93; Journal Issue: 15; Related Information: CES partners with Brookhaven National Laboratory (BNL); Argonne National Laboratory; University of Illinois, Urbana-Champaign; Los Alamos National Laboratory; Journal ID: ISSN 2469-9950

Publisher:: American Physical Society (APS)

Country of Publication:: United States

Language:: English

Subject:: 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; phonons; thermal conductivity; energy storage (including batteries and capacitors); superconductivity; defects; spin dynamics

Citation Formats


                    Leong, Zhidong, and Phillips, Philip. Effects of Coulomb interactions on the superconducting gaps in iron-based superconductors.  United States: N. p., 2016. 
        Web.  doi:10.1103/PhysRevB.93.155159.

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                    Leong, Zhidong, & Phillips, Philip. Effects of Coulomb interactions on the superconducting gaps in iron-based superconductors.  United States.  https://doi.org/10.1103/PhysRevB.93.155159

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                    Leong, Zhidong, and Phillips, Philip. Wed .  
        "Effects of Coulomb interactions on the superconducting gaps in iron-based superconductors".  United States.  https://doi.org/10.1103/PhysRevB.93.155159.  https://www.osti.gov/servlets/purl/1387865.

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@article{osti_1387865,

  title        = {Effects of Coulomb interactions on the superconducting gaps in iron-based superconductors},

  author       = {Leong, Zhidong and Phillips, Philip},

  abstractNote = {Recent angle-resolved photoemission spectroscopy measurements of Co-doped LiFeAs report a large and robust superconducting gap on the Γ-centered hole band that lies 8 meV below the Fermi level. We show that, unlike a conventional superconductor described by BCS theory, a multiband system with strong interband Coulomb interactions can explain these observations. We model LiFeAs with a five-band model in which the shallow hole band is coupled with the other bands by only Coulomb interactions. Using Eliashberg theory, we find reasonable interaction parameters that reproduce the Tc and all five gaps of LiFeAs. The energy independence of the Coulomb interactions then ensures the robustness of the gap induced on the shallow band. Furthermore, due to the repulsive nature of the Coulomb interactions, the gap changes sign between the shallow band and the other hole pockets, corresponding to an unconventional s± gap symmetry. Unlike other families of iron-based superconductors, the gap symmetry of LiFeAs has not been ascertained experimentally. Finally, the experimental implications of this sign-changing state are discussed.},

  doi          = {10.1103/PhysRevB.93.155159},

  url          = {https://www.osti.gov/biblio/1387865},
  journal      = {Physical Review B},

  issn         = {2469-9950},

  number       = 15,

  volume       = 93,

  place        = {United States},

  year         = {2016},

  month        = {4}

}

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Works referenced in this record:

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Works referencing / citing this record:

Lifthitz Transition and Shadow Gap in Li(Fe1−xCox)As Investigated by STM/STS
journal, June 2019

Liu, Ruizhe; Ye, Zhiyang; Wang, Jihui
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Title: Effects of Coulomb interactions on the superconducting gaps in iron-based superconductors

Abstract

Citation Formats

Superconducting gap in LiFeAs from three-dimensional spin-fluctuation pairing calculations journal, November 2013

A phenomenological multiband Eliashberg model for LiFeAs journal, April 2013

Properties of boson-exchange superconductors journal, October 1990

Interband superconductivity: Contrasts between Bardeen-Cooper-Schrieffer and Eliashberg theories journal, February 2009

Unconventional Anisotropic s -Wave Superconducting Gaps of the LiFeAs Iron-Pnictide Superconductor journal, January 2012

Sign inversion in the superconducting order parameter of LiFeAs inferred from Bogoliubov quasiparticle interference journal, March 2014

Unconventional Superconductivity with a Sign Reversal in the Order Parameter of LaFeAsO 1 − x F x journal, July 2008

Multiple Nodeless Superconducting Gaps in (Ba 0.6 K 0.4 )Fe 2 As 2 Superconductor from Angle-Resolved Photoemission Spectroscopy journal, December 2008

LiFeAs: An intrinsic FeAs-based superconductor with T c = 18 K journal, August 2008

Spin dynamics and orbital-antiphase pairing symmetry in iron-based superconductors journal, October 2014

Antiferromagnetic spin fluctuations in LiFeAs observed by neutron scattering journal, June 2011

Anisotropic Energy Gaps of Iron-Based Superconductivity from Intraband Quasiparticle Interference in LiFeAs journal, May 2012

Solving the Eliashberg equations by means ofN-point Pad� approximants journal, November 1977

Observation of strong electron pairing on bands without Fermi surfaces in LiFe1−xCoxAs journal, January 2015

Observation of Fermi-surface–dependent nodeless superconducting gaps in Ba 0.6 K 0.4 Fe 2 As 2 journal, July 2008

Superconductivity from repulsion in LiFeAs: Novel s -wave symmetry and potential time-reversal symmetry breaking journal, April 2014

Insight into the physics of Fe-pnictides from optical and T= 0 penetration depth data journal, December 2010

Spin-Fluctuation-Induced Non-Fermi-Liquid Behavior with Suppressed Superconductivity in LiFe 1 − x Co x As journal, September 2015

Superconducting state of the iron pnictide LiFeAs: A combined density-functional and functional-renormalization-group study journal, December 2011

Isotropic superconducting gaps with enhanced pairing on electron Fermi surfaces in FeTe 0.55 Se 0.45 journal, March 2012

Superconductivity in an electron band just above the Fermi level: possible route to BCS-BEC superconductivity journal, February 2014

Phase diagram and electronic indication of high-temperature superconductivity at 65 K in single-layer FeSe films journal, May 2013

High-temperature superconductivity in iron-based materials journal, August 2010

Electronic origin of high-temperature superconductivity in single-layer FeSe superconductor journal, January 2012

Reproduction of experimental gap structure in LiFeAs based on orbital-spin fluctuation theory: s + + -wave, s ± -wave, and hole- s ± -wave states journal, July 2014

Shallow pockets and very strong coupling superconductivity in FeSexTe1−x journal, February 2012

Identifying the 'fingerprint' of antiferromagnetic spin fluctuations in iron pnictide superconductors journal, December 2014

Superconductivity without Nesting in LiFeAs journal, August 2010

Experimental detection of sign-reversal pairing in iron-based superconductors journal, March 2009

Lifthitz Transition and Shadow Gap in Li(Fe1−xCox)As Investigated by STM/STS journal, June 2019

Strong correlations, strong coupling, and s -wave superconductivity in hole-doped BaFe 2 As 2 single crystals journal, November 2016

Superconducting gap in LiFeAs from three-dimensional spin-fluctuation pairing calculations
journal, November 2013

A phenomenological multiband Eliashberg model for LiFeAs
journal, April 2013

Properties of boson-exchange superconductors
journal, October 1990

Interband superconductivity: Contrasts between Bardeen-Cooper-Schrieffer and Eliashberg theories
journal, February 2009

Unconventional Anisotropic $s$ -Wave Superconducting Gaps of the LiFeAs Iron-Pnictide Superconductor
journal, January 2012

Sign inversion in the superconducting order parameter of LiFeAs inferred from Bogoliubov quasiparticle interference
journal, March 2014

Unconventional Superconductivity with a Sign Reversal in the Order Parameter of ${LaFeAsO}_{1 - x} F_{x}$
journal, July 2008

Multiple Nodeless Superconducting Gaps in (Ba _0.6 K _0.4 )Fe ₂ As ₂ Superconductor from Angle-Resolved Photoemission Spectroscopy
journal, December 2008

LiFeAs: An intrinsic FeAs-based superconductor with $T_{c} = 18 K$
journal, August 2008

Spin dynamics and orbital-antiphase pairing symmetry in iron-based superconductors
journal, October 2014

Antiferromagnetic spin fluctuations in LiFeAs observed by neutron scattering
journal, June 2011

Anisotropic Energy Gaps of Iron-Based Superconductivity from Intraband Quasiparticle Interference in LiFeAs
journal, May 2012

Solving the Eliashberg equations by means ofN-point Pad� approximants
journal, November 1977

Observation of strong electron pairing on bands without Fermi surfaces in LiFe1−xCoxAs
journal, January 2015

Observation of Fermi-surface–dependent nodeless superconducting gaps in Ba _0.6 K _0.4 Fe ₂ As ₂
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Superconductivity from repulsion in LiFeAs: Novel $s$ -wave symmetry and potential time-reversal symmetry breaking
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Insight into the physics of Fe-pnictides from optical and T= 0 penetration depth data
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Spin-Fluctuation-Induced Non-Fermi-Liquid Behavior with Suppressed Superconductivity in ${LiFe}_{1 - x} {Co}_{x} As$
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Superconducting state of the iron pnictide LiFeAs: A combined density-functional and functional-renormalization-group study
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Phase diagram and electronic indication of high-temperature superconductivity at 65 K in single-layer FeSe films
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Electronic origin of high-temperature superconductivity in single-layer FeSe superconductor
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Reproduction of experimental gap structure in LiFeAs based on orbital-spin fluctuation theory: $s_{+ +}$ -wave, $s_{\pm}$ -wave, and hole- $s_{\pm}$ -wave states
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Shallow pockets and very strong coupling superconductivity in FeSexTe1−x
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Identifying the 'fingerprint' of antiferromagnetic spin fluctuations in iron pnictide superconductors
journal, December 2014

Superconductivity without Nesting in LiFeAs
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Lifthitz Transition and Shadow Gap in Li(Fe1−xCox)As Investigated by STM/STS
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Strong correlations, strong coupling, and $s$ -wave superconductivity in hole-doped ${BaFe}_{2} {As}_{2}$ single crystals
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