Robustness of s-Wave Pairing in Electron-Overdoped A 1-yFe 2-xSe2 (A=K,Cs)

Chen Fang, Yang Le Wu, Ronny Thomale, Andrei B. Bernevig, Jiangping Hu

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63 Scopus citations


Using self-consistent mean-field and functional renormalization-group approaches, we show that s-wave pairing symmetry is robust in the heavily electron-doped iron chalcogenides AFe 2-xSe2, where A=K,Cs. Recent neutron scattering experiments suggest that the effective nearest-neighbor spin exchange may be ferromagnetic in chalcogenides. This is different from the iron pnictides, where the nearest-neighbor magnetic exchange coupling is believed to be antiferromagnetic and leads to strong competition between s-wave and d-wave pairing in the electron-overdoped region. Our finding of a robust s-wave pairing in (K,Cs)Fe 2-xSe2 differs from the d-wave pairing result obtained by other theories where nonlocal bare interaction terms and the next-to-nearest-neighbor J2 term are underestimated. Detecting the pairing symmetry in (K,Cs)Fe 2-xSe2 may hence provide important insights regarding the mechanism of superconducting pairing in iron-based superconductors.

Original languageEnglish (US)
Pages (from-to)1-13
Number of pages13
JournalPhysical Review X
Issue number1
StatePublished - 2011

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


  • Condensed Matter Physics
  • Strongly Correlated Materials
  • Superconductivity


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