Journal Article

FZJ-2020-01343

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Neutron Spin Resonance in the Heavily Hole-Doped KFe 2 As 2 Superconductor

Shen, S. ; Zhang, X. ; Wo, H. ; Shen, Y. ; Feng, Y. ; Schneidewind, A.FZJ* ; Čermák, P. ; Wang, W. ; Zhao, J. (Corresponding author)

2020
APS College Park, Md.

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Please use a persistent id in citations: http://hdl.handle.net/2128/24439  doi:10.1103/PhysRevLett.124.017001

Abstract: We report high-resolution neutron scattering measurements of the low energy spin fluctuations ofKFe2As2, the end member of the hole-doped Ba1−xKxFe2As2family with only hole pockets, above andbelow its superconducting transition temperatureTc(∼3.5K). Our data reveal clear spin fluctuations at theincommensurate wave vector (0.5δ,0,L), (δ¼0.2) (1-Fe unit cell), which exhibitL-modulationpeaking atL¼0.5. Upon cooling to the superconducting state, the incommensurate spin fluctuationsgradually open a spin gap and form a sharp spin resonance mode. The incommensurability (2δ¼0.4)ofthe resonance mode (∼1.2meV) is considerably larger than the previously reported value (2δ≈0.32)athigher energies (≥∼6meV). The determination of the momentum structure of spin fluctuation in the lowenergy limit allows a direct comparison with the realistic Fermi surface and superconducting gap structure.Our results point to ans-wave pairing with a reversed sign between the hole pockets near the zone center inKFe2As2.

Keyword(s): Energy (1st) ; Magnetism (2nd) ; Condensed Matter Physics (2nd)

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Contributing Institute(s):

1. JCNS-FRM-II (JCNS-FRM-II)
2. Streumethoden (JCNS-2)

Research Program(s):

1. 6212 - Quantum Condensed Matter: Magnetism, Superconductivity (POF3-621) (POF3-621)
2. 6G15 - FRM II / MLZ (POF3-6G15) (POF3-6G15)
3. 6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623) (POF3-623)

Experiment(s):

1. PANDA: Cold three axes spectrometer (SR2)

Appears in the scientific report 2020

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