Emergence of fully gappeds++-wave and nodald-wave states mediated by orbital and spin fluctuations in a ten-orbital model of KFe2Se2

2011/02/28 by Tetsuro Saito, Seiichiro Onari, Hiroshi Kontani · 1 citation
Materials Science · Physics and Astronomy · #Iron-based superconductors research #Rare-earth and actinide compounds #cond-mat.str-el #cond-mat.supr-con

paper · pdf · doi:10.1103/physrevb.83.140512

published as Phys. Rev. B 83, 140512(R) (2011) · 5 pages, 4 figures, to be published in Phys. Rev. B (Rapid Communication)

arxiv created 2011/04/08 · openalex publication_date 2011/04/22 · arxiv updated 2011/04/26 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31

Abstract

We study the superconducting state in recently discovered high-T_c superconductor K_xFe₂Se₂ 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 K_xFe₂Se₂ 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 T_c.

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