Charge and quadrupole fluctuations and gap anisotropy in BiS2-based superconductors

Katsuhiro Suzuki, Hidetomo Usui, Kazuhiko Kuroki, and Hiroaki Ikeda
Phys. Rev. B 96, 024513 – Published 21 July 2017

Abstract

Recent angle-resolved spectroscopy in BiS2-based superconductors has indicated that the superconducting gap amplitude possesses remarkable anisotropy and/or a sign change on a small Fermi pocket around the X point. It implies a possibility of an unconventional pairing state. Here we study the gap anisotropy in superconductivity mediated by inherent charge and quadrupole fluctuations in an extended Hubbard model, which includes intersite interaction between Bi and S atoms. The first-principles downfolded band structure is composed of Bi 6px/py and S 3px/py orbitals on a BiS2 single layer. Evaluating the linearized gap equation, we find that the ferroic charge and quadrupole fluctuation driven by the intersite interaction leads to a fully gapped dx2y2-wave pairing state, in which the gap amplitude has sizable anisotropy on the Fermi surface.

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  • Received 5 March 2017

DOI:https://doi.org/10.1103/PhysRevB.96.024513

©2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Katsuhiro Suzuki1, Hidetomo Usui2, Kazuhiko Kuroki2, and Hiroaki Ikeda3

  • 1Research Organization of Science and Technology, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
  • 2Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan
  • 3Department of Physics, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan

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Issue

Vol. 96, Iss. 2 — 1 July 2017

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