Stabilization of s-wave superconductivity through arsenic p-orbital hybridization in electron-doped BaFe2As2

David W. Tam, Tom Berlijn, and Thomas A. Maier
Phys. Rev. B 98, 024507 – Published 12 July 2018

Abstract

Using random-phase approximation spin-fluctuation theory, we study the influence of the hybridization between iron d orbitals and pnictide p orbitals on the superconducting pairing state in iron-based superconductors. The calculations are performed for a 16-orbital Hubbard-Hund tight-binding model of BaFe2As2 that includes the As-p orbital degrees of freedom in addition to the Fe-d orbitals and compared to calculations for a 10-orbital Fe-d only model. In both models we find a leading s± pairing state and a subleading dx2y2-wave state in the parent compound. Upon doping, we find that the s± state remains the leading state in the 16-orbital model up to a doping level of 0.475 electrons per unit cell, at which the hole Fermi-surface pockets at the zone center start to disappear. This is in contrast to the 10-orbital model, where the d-wave state becomes the leading state at a doping of less than 0.2 electrons. This improved stability of s± pairing is found to arise from a decrease of dxy orbital weight on the electron pockets due to hybridization with the As-p orbitals and the resulting reduction of near (π,π) spin-fluctuation scattering which favors the competing d-wave state. These results show that the orbital dependent hybridization of Fermi-surface Bloch states with the usually neglected p-orbital states is an important ingredient in an improved itinerant pairing theory.

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  • Received 11 May 2018

DOI:https://doi.org/10.1103/PhysRevB.98.024507

©2018 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

David W. Tam1, Tom Berlijn2, and Thomas A. Maier2,*

  • 1Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
  • 2Center for Nanophase Materials Sciences and Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6494, USA

  • *maierta@ornl.gov

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Vol. 98, Iss. 2 — 1 July 2018

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