Emergence of fully gapped s++-wave and nodal d-wave states mediated by orbital and spin fluctuations in a ten-orbital model of KFe 2Se2

Tetsuro Saito, Seiichiro Onari, Hiroshi Kontani

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

We study the superconducting state in recently discovered high-T c superconductor KxFe2Se2 based on the ten-orbital Hubbard-Holstein model without hole pockets. When the Coulomb interaction is large, a spin-fluctuation-mediated d-wave state appears due to the nesting between electron pockets. Interestingly, the symmetry of the body-centered tetragonal structure in KxFe2Se2 requires the existence of nodes in the d-wave gap, although a fully gapped d-wave state is realized in the case of a simple tetragonal structure. In the presence of moderate electron-phonon interaction due to Fe-ion optical modes, however, orbital fluctuations give rise to the fully gapped s++-wave state without sign reversal. Therefore, both superconducting states are distinguishable by careful measurements of the gap structure or the impurity effect on Tc.

Original languageEnglish
Article number140512
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume83
Issue number14
DOIs
Publication statusPublished - Apr 22 2011
Externally publishedYes

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Spin fluctuations
orbitals
Hubbard model
Electron-phonon interactions
electron phonon interactions
Coulomb interactions
Superconducting materials
Impurities
Ions
impurities
Electrons
symmetry
ions
electrons
interactions

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

Cite this

Emergence of fully gapped s++-wave and nodal d-wave states mediated by orbital and spin fluctuations in a ten-orbital model of KFe 2Se2 . / Saito, Tetsuro; Onari, Seiichiro; Kontani, Hiroshi.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 83, No. 14, 140512, 22.04.2011.

Research output: Contribution to journalArticle

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