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Title: Orbital Selective Spin Excitations and their Impact on Superconductivity of LiFe 1 - x Co x As

We use neutron scattering to study spin excitations in single crystals of LiFe 0.88Co 0.12As, which is located near the boundary of the superconducting phase of LiFe 1-xCo xAs and exhibits non- Fermi-liquid behavior indicative of a quantum critical point. By comparing spin excitations of LiFe 0.88Co 0.12As with a combined density functional theory (DFT) and dynamical mean field theory (DMFT) calculation, we conclude that wave-vector correlated low energy spin excitations are mostly from the dxy orbitals, while high-energy spin excitations arise from the dyz and dxz orbitals. Unlike most iron pnictides, the strong orbital selective spin excitations in LiFeAs family cannot be described by anisotropic Heisenberg Hamiltonian. While the evolution of low-energy spin excitations of LiFe 1-xCo xAs are consistent with electron-hole Fermi surface nesting condition for the dxy orbital, the reduced superconductivity in LiFe 0.88Co 0.12As suggests that Fermi surface nesting conditions for the dyz and dxz orbitals are also important for superconductivity in iron pnictides.
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [4] ;  [4] ;  [1] ;  [5] ;  [3] ;  [6] ;  [7] ;  [8] ;  [4] ;  [9]
  1. Rice Univ., Houston, TX (United States)
  2. Beijing Normal Univ. (China); Rutgers Univ., Piscataway, NJ (United States)
  3. Chinese Academy of Sciences (CAS), Beijing (China)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  5. Univ. of California, Berkeley, CA (United States)
  6. Chinese Academy of Sciences (CAS), Beijing (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)
  7. Rutgers Univ., Piscataway, NJ (United States)
  8. Rutgers Univ., Piscataway, NJ (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
  9. Rice Univ., Houston, TX (United States); Beijing Normal Univ. (China)
Publication Date:
Report Number(s):
BNL-114720-2017-JA
Journal ID: ISSN 0031-9007; PRLTAO; R&D Project: PM051; KC0213010
Grant/Contract Number:
SC0012704; SC0012311; AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 116; Journal Issue: 24; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society (APS)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1412753
Alternate Identifier(s):
OSTI ID: 1257667