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Title: Structure of spin excitations in heavily electron-doped Li 0.8Fe 0.2ODFeSe superconductors

Heavily electron-doped iron-selenide high-transition-temperature (high-T c) superconductors, which have no hole Fermi pockets, but have a notably high T c, have challenged the prevailing s± pairing scenario originally proposed for iron pnictides containing both electron and hole pockets. The microscopic mechanism underlying the enhanced superconductivity in heavily electron-doped iron-selenide remains unclear. Here, we used neutron scattering to study the spin excitations of the heavily electron-doped iron-selenide material Li 0.8Fe 0.2ODFeSe (T c = 41 K). Our data revealed nearly ring-shaped magnetic resonant excitations surrounding (π, π) at ~21 meV. As the energy increased, the spin excitations assumed a diamond shape, and they dispersed outward until the energy reached ~60 meV and then inward at higher energies. The observed energy-dependent momentum structure and twisted dispersion of spin excitations near (π, π) are analogous to those of hole-doped cuprates in several aspects, thus implying that such spin excitations are essential for the remarkably high T c in these materials.
Authors:
 [1] ; ORCiD logo [1] ;  [1] ;  [1] ; ORCiD logo [2] ; ORCiD logo [3] ;  [1] ;  [1] ;  [1] ;  [4] ;  [5] ; ORCiD logo [6]
  1. Fudan Univ., Shanghai (China). State Key Laboratory of Surface Physics and Department of Physics
  2. Technical University of Munich (Germany). Heinz Maier-Leibnitz Zentrum (MLZ)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States).Quantum Condensed Matter Division; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy
  4. Beijing Normal University (China). Department of Physics and Center for Advanced Quantum Studies
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Computer Science and Mathematics Division, Center for Nanophase Materials Sciences, and Materials Science and Technology Division
  6. Fudan Univ., Shanghai (China). State Key Laboratory of Surface Physics and Department of Physics; Collaborative Innovation Center of Advanced Microstructures, Nanjing (China)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1399978