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Persistent high-energy spin excitations in iron-pnictide superconductors

DOI: 10.1038/ncomms2428 DOI Help

Authors: Ke-jin Zhou (Diamond Light Source) , Yao-bo Huang (Swiss Light Source; Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences) , Claude Monney (Swiss Light Source) , Xi Dai (Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences) , Vladimir N. Strocov (Swiss Light Source) , Nan-lin Wang (Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences) , Zhi-guo Chen (Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences) , Chenglin Zhang (The University of Tennessee) , Pengcheng Dai (Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences; The University of Tennessee) , Luc Patthey (Swiss Light Source; SwissFEL) , Jeroen Van Den Brink (Institute for Theoretical Solid State Physics, IFW Dresden) , Hong Ding (Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences) , Thorsten Schmitt (Swiss Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Communications , VOL 4 , PAGES 136-144

State: Published (Approved)
Published: February 2013

Abstract: Motivated by the premise that superconductivity in iron-based superconductors is unconventional and mediated by spin fluctuations, an intense research effort has been focused on characterizing the spin-excitation spectrum in the magnetically ordered parent phases of the Fe pnictides and chalcogenides. For these undoped materials, it is well established that the spin-excitation spectrum consists of sharp, highly dispersive magnons. The fate of these high-energy magnetic modes upon sizable doping with holes is hitherto unresolved. Here we demonstrate, using resonant inelastic X-ray scattering, that optimally hole-doped superconducting Ba0.6K0.4Fe2As2 retains well-defined, dispersive high-energy modes of magnetic origin. These paramagnon modes are softer than, though as intense as, the magnons of undoped antiferromagnetic BaFe2As2. The persistence of spin excitations well into the superconducting phase suggests that the spin fluctuations in Fe-pnictide superconductors originate from a distinctly correlated spin state. This connects Fe pnictides to cuprates, for which, in spite of fundamental electronic structure differences, similar paramagnons are present.

Journal Keywords: Physical Sciences; Condensed Matter

Subject Areas: Physics

Facility: Swiss Light Source