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Title: Orbital selective pairing and gap structures of iron-based superconductors

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Emergent Superconductivity (CES)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1388893
DOE Contract Number:
AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review B; Journal Volume: 95; Journal Issue: 17; Related Information: CES partners with Brookhaven National Laboratory (BNL); Argonne National Laboratory; University of Illinois, Urbana-Champaign; Los Alamos National Laboratory
Country of Publication:
United States
Language:
English
Subject:
phonons, thermal conductivity, energy storage (including batteries and capacitors), superconductivity, defects, spin dynamics

Citation Formats

Kreisel, Andreas, Andersen, Brian M., Sprau, P. O., Kostin, A., Davis, J. C. Séamus, and Hirschfeld, P. J.. Orbital selective pairing and gap structures of iron-based superconductors. United States: N. p., 2017. Web. doi:10.1103/PhysRevB.95.174504.
Kreisel, Andreas, Andersen, Brian M., Sprau, P. O., Kostin, A., Davis, J. C. Séamus, & Hirschfeld, P. J.. Orbital selective pairing and gap structures of iron-based superconductors. United States. doi:10.1103/PhysRevB.95.174504.
Kreisel, Andreas, Andersen, Brian M., Sprau, P. O., Kostin, A., Davis, J. C. Séamus, and Hirschfeld, P. J.. 2017. "Orbital selective pairing and gap structures of iron-based superconductors". United States. doi:10.1103/PhysRevB.95.174504.
@article{osti_1388893,
title = {Orbital selective pairing and gap structures of iron-based superconductors},
author = {Kreisel, Andreas and Andersen, Brian M. and Sprau, P. O. and Kostin, A. and Davis, J. C. Séamus and Hirschfeld, P. J.},
abstractNote = {},
doi = {10.1103/PhysRevB.95.174504},
journal = {Physical Review B},
number = 17,
volume = 95,
place = {United States},
year = 2017,
month = 5
}
  • We discuss the in uence on spin-fluctuation pairing theory of orbital selective strong correlation effects in Fe-based superconductors, particularly Fe chalcogenide systems. We propose that a key ingredient for an improved itinerant pairing theory is orbital selectivity, i.e., incorporating the reduced coherence of quasiparticles occupying specific orbital states. This modifies the usual spin-fluctuation via suppression of pair scattering processes involving those less coherent states and results in orbital selective Cooper pairing of electrons in the remaining states. We show that this paradigm yields remarkably good agreement with the experimentally observed anisotropic gap structures in both bulk and monolayer FeSe, asmore » well as LiFeAs, indicating that orbital selective Cooper pairing plays a key role in the more strongly correlated iron-based superconductors.« less
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  • The theoretical need to study the properties of the Fe-based high-Tc superconductors using reliable manybody techniques has highlighted the importance of determining what is the minimum number of orbital degrees of freedom that will capture the physics of these materials. While the shape of the Fermi surface FS obtained with the local-density approximation LDA can be reproduced by a two-orbital model, it has been argued that the bands that cross the chemical potential result from the strong hybridization of three of the Fe 3d orbitals. For this reason, a three orbital Hamiltonian for LaOFeAs obtained with the Slater-Koster formalism bymore » considering the hybridization of the As p orbitals with the Fe dxz, dyz, and dxy orbitals is discussed here. This model reproduces qualitatively the FS shape and orbital composition obtained by LDA calculations for undoped LaOFeAs when four electrons per Fe are considered. Within a mean-field approximation, its magnetic and orbital properties in the undoped case are here described for intermediate values of J/U. Increasing the Coulomb repulsion U at zero temperature, four different regimes are obtained: 1 paramagnetic, 2 magnetic ,0 spin order, 3 the same ,0 spin order but now including orbital order, and finally 4 a magnetic and orbital ordered insulator. The spin-singlet pairing operators allowed by the lattice and orbital symmetries are also constructed. It is found that for pairs of electrons involving up to diagonal nearest-neighbors sites, the only fully gapped and purely intraband spin-singlet pairing operator is given by k= fkdk,, d k,, with fk=1 or cos kx cos ky which would arise only if the electrons in all different orbitals couple with equal strength to the source of pairing.« less