%0 Journal Article
%A Shen, Shoudong
%A Zhang, Xiaowen
%A Wo, Hongliang
%A Shen, Yao
%A Feng, Yu
%A Schneidewind, A.
%A Čermák, P.
%A Wang, Wenbin
%A Zhao, Jun
%T Neutron Spin Resonance in the Heavily Hole-Doped KFe 2 As 2 Superconductor
%J Physical review letters
%V 124
%N 1
%@ 1079-7114
%C College Park, Md.
%I APS
%M FZJ-2020-01343
%P 017001
%D 2020
%X 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.
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:31976731
%U <Go to ISI:>//WOS:000505496400003
%R 10.1103/PhysRevLett.124.017001
%U https://juser.fz-juelich.de/record/874252