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Title: Sensitivity of the superconducting state and magnetic susceptibility to key aspects of electronic structure in ferropnictides

Abstract

Experiments on the iron-pnictide superconductors appear to show some materials where the ground state is fully gapped, and others where low-energy excitations dominate, possibly indicative of gap nodes. Within the framework of a five-orbital spin fluctuation theory for these systems, we discuss how changes in the doping, the electronic structure or interaction parameters can tune the system from a fully gapped to a nodal sign-changing gap with s-wave (A{sub 1g}) symmetry (s{sup {+-}}). In particular, we focus on the role of the hole pocket at the ({pi}, {pi}) point of the unfolded Brillouin zone, identified as crucial to the pairing by Kuroki et al (2009 Phys. Rev. B 79 224511), and show that its presence leads to additional nesting of hole and electron pockets, which stabilizes the isotropic s{sup {+-}} state. The pocket's contribution to the pairing can be tuned by doping, surface effects and by changes in interaction parameters, which we examine. Analytic expressions for orbital pairing vertices calculated within the random phase approximation (RPA) fluctuation exchange approximation allow us to draw connections between aspects of the electronic structure, interaction parameters and the form of the superconducting gap.

Authors:
 [1];  [1];  [2];  [2];  [2];  [3]
  1. ORNL
  2. University of Florida
  3. University of California, Santa Barbara
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Center for Nanophase Materials Sciences
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
986824
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
New Journal of Physics
Additional Journal Information:
Journal Volume: 12; Journal Issue: 7; Journal ID: ISSN 1367-2630
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; APPROXIMATIONS; BRILLOUIN ZONES; ELECTRONIC STRUCTURE; ELECTRONS; ENERGY GAP; FLUCTUATIONS; GROUND STATES; IRON COMPOUNDS; MAGNETIC SUSCEPTIBILITY; PNICTIDES; RANDOM PHASE APPROXIMATION; SENSITIVITY; SPIN; SUPERCONDUCTORS; SYMMETRY

Citation Formats

Kemper, Alexander F, Maier, Thomas A, Graser, Siegfried, Cheng, Hai-Ping, Hirschfeld, Peter, and Scalapino, Douglas. Sensitivity of the superconducting state and magnetic susceptibility to key aspects of electronic structure in ferropnictides. United States: N. p., 2010. Web. doi:10.1088/1367-2630/12/7/073030.
Kemper, Alexander F, Maier, Thomas A, Graser, Siegfried, Cheng, Hai-Ping, Hirschfeld, Peter, & Scalapino, Douglas. Sensitivity of the superconducting state and magnetic susceptibility to key aspects of electronic structure in ferropnictides. United States. doi:10.1088/1367-2630/12/7/073030.
Kemper, Alexander F, Maier, Thomas A, Graser, Siegfried, Cheng, Hai-Ping, Hirschfeld, Peter, and Scalapino, Douglas. Fri . "Sensitivity of the superconducting state and magnetic susceptibility to key aspects of electronic structure in ferropnictides". United States. doi:10.1088/1367-2630/12/7/073030.
@article{osti_986824,
title = {Sensitivity of the superconducting state and magnetic susceptibility to key aspects of electronic structure in ferropnictides},
author = {Kemper, Alexander F and Maier, Thomas A and Graser, Siegfried and Cheng, Hai-Ping and Hirschfeld, Peter and Scalapino, Douglas},
abstractNote = {Experiments on the iron-pnictide superconductors appear to show some materials where the ground state is fully gapped, and others where low-energy excitations dominate, possibly indicative of gap nodes. Within the framework of a five-orbital spin fluctuation theory for these systems, we discuss how changes in the doping, the electronic structure or interaction parameters can tune the system from a fully gapped to a nodal sign-changing gap with s-wave (A{sub 1g}) symmetry (s{sup {+-}}). In particular, we focus on the role of the hole pocket at the ({pi}, {pi}) point of the unfolded Brillouin zone, identified as crucial to the pairing by Kuroki et al (2009 Phys. Rev. B 79 224511), and show that its presence leads to additional nesting of hole and electron pockets, which stabilizes the isotropic s{sup {+-}} state. The pocket's contribution to the pairing can be tuned by doping, surface effects and by changes in interaction parameters, which we examine. Analytic expressions for orbital pairing vertices calculated within the random phase approximation (RPA) fluctuation exchange approximation allow us to draw connections between aspects of the electronic structure, interaction parameters and the form of the superconducting gap.},
doi = {10.1088/1367-2630/12/7/073030},
journal = {New Journal of Physics},
issn = {1367-2630},
number = 7,
volume = 12,
place = {United States},
year = {2010},
month = {1}
}