%0 Journal Article
%A Zhang, Chenglin
%A Song, Yu
%A Regnault, L.-P.
%A Su, Yixi
%A Enderle, M.
%A Kulda, J.
%A Tan, Guotai
%A Sims, Zachary C.
%A Egami, Takeshi
%A Si, Qimiao
%A Dai, Pengcheng
%T Anisotropic neutron spin resonance in underdoped superconducting ${\mathrm{NaFe}}_{1-x}{\mathrm{Co}}_{x}\mathrm{As}$
%J Physical review / B
%V 90
%N 14
%@ 1098-0121
%C College Park, Md.
%I APS
%M FZJ-2014-05605
%P 140502
%D 2014
%X We use polarized inelastic neutron scattering (INS) to study spin excitations in superconducting NaFe0.985Co0.015As (C15) with static antiferromagnetic (AF) order along the a axis of the orthorhombic structure and NaFe0.935Co0.045As (C45) without AF order. In previous unpolarized INS work, spin excitations in C15 were found to have a dispersive sharp resonance near Er1=3.25 meV and a broad dispersionless mode at Er2=6 meV. Our neutron polarization analysis reveals that the dispersive resonance in C15 is highly anisotropic and polarized along the a and c axes, while the dispersionless mode is isotropic similar to that of C45. Since the a-axis polarized spin excitations of the anisotropic resonance appear below Tc, our data suggests that the itinerant electrons contributing to the magnetism are also coupled to the superconductivity.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000344017500002
%R 10.1103/PhysRevB.90.140502
%U https://juser.fz-juelich.de/record/172056