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Near-degeneracy of several pairing channels in multiorbital models for the Fe pnictides

Journal Article · · New Journal of Physics
 [1];  [2];  [1];  [3]
  1. University of Florida, Gainesville, FL (United States)
  2. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
  3. University of California, Santa Barbara, CA (United States)
+ Show Author Affiliations
Weak-coupling approaches to the pairing problem in the iron pnictide superconductors have predicted a wide variety of superconducting ground states. We argue here that this is due both to the inadequacy of certain approximations to the effective low-energy band structure, and to the natural near degeneracy of different pairing channels in superconductors with many distinct Fermi surface sheets. In particular, we review attempts to construct two-orbital effective band models, the argument for their fundamental inconsistency with the symmetry of these materials, and compare the dynamical susceptibilities of two- and five-orbital tight-binding models. We then present results for the magnetic properties, pairing interactions and pairing instabilities within a five-orbital tight-binding random phase approximation model. We discuss the robustness of these results for different dopings, interaction strengths and variations in band structures. Within the parameter space explored, an anisotropic, sign-changing s-wave (A1g) state and a dx2-y2 (B1g) state are nearly degenerate, due to the near nesting of Fermi surface sheets.
Research Organization:
University of Florida, Gainesville, FL (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
Grant/Contract Number:
FG02-05ER46236
OSTI ID:
2484113
Journal Information:
New Journal of Physics, Journal Name: New Journal of Physics Journal Issue: 2 Vol. 11; ISSN 1367-2630
Publisher:
IOP PublishingCopyright Statement
Country of Publication:
United States
Language:
English

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Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY