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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:
 [1];  [1]
  1. Univ. of Illinois at Urbana-Champaign, IL (United States)
Publication Date:
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.
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
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.
@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}
}

Journal Article:

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Cited by: 1 work
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Works referenced in this record:

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


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


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


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


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


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


    Works referencing / citing this record:

    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