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Nematic and superconducting order in a three‐band model for the iron superconductors
Author(s) -
Honerkamp Carsten
Publication year - 2017
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201600151
Subject(s) - pairing , condensed matter physics , superconductivity , physics , sign (mathematics) , atomic orbital , liquid crystal , antiferromagnetism , spin (aerodynamics) , quantum mechanics , electron , mathematics , mathematical analysis , thermodynamics
We investigate collective ordering tendencies in a three‐band model for iron superconductors, driven by intra‐ and inter‐orbital local interactions, by means of a renormalization group (RG) approach. Our study extends earlier fundamental RG studies by Chubukov et al. [Phys. Rev. B 78 , 134512 (2008)] by allowing the flowing interactions to be orbital‐dependent. While for small inter‐orbital repulsion U ′ , we retrieve the previous picture of a constructive interplay between antiferromagnetic spin‐density wave ordering and sign‐changing s ‐wave pairing, for larger U ′ , d xz / yz ’“nematic” orbital ordering becomes strong and changes the groundstate of the undoped or slightly doped system qualitatively. At the transition between the two regimes, both sign‐changing pairing and sign‐changing d xz / yz ‐nematic are most pronounced. Our results suggest a much richer range of possibilities for the ground states of iron superconductors and related materials and shows how nematic order can act as an additional source for unconventional Cooper pairing. For the strongly electron‐doped case without hole pockets we also find a novel pairing that has no sign‐change as function of the wavevector but changes sign between the d xy and the d xz / yzorbitals.