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 journalArticlepeer-review

59 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

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Fingerprint Dive into the research topics of 'Emergence of fully gapped s<sub>++</sub>-wave and nodal d-wave states mediated by orbital and spin fluctuations in a ten-orbital model of KFe <sub>2</sub>Se<sub>2</sub>'. Together they form a unique fingerprint.

Cite this