TY  - JOUR
AU  - Zhang, Chenglin
AU  - Song, Yu
AU  - Regnault, L.-P.
AU  - Su, Yixi
AU  - Enderle, M.
AU  - Kulda, J.
AU  - Tan, Guotai
AU  - Sims, Zachary C.
AU  - Egami, Takeshi
AU  - Si, Qimiao
AU  - Dai, Pengcheng
TI  - Anisotropic neutron spin resonance in underdoped superconducting ${\mathrm{NaFe}}_{1-x}{\mathrm{Co}}_{x}\mathrm{As}$
JO  - Physical review / B
VL  - 90
IS  - 14
SN  - 1098-0121
CY  - College Park, Md.
PB  - APS
M1  - FZJ-2014-05605
SP  - 140502
PY  - 2014
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000344017500002
DO  - DOI:10.1103/PhysRevB.90.140502
UR  - https://juser.fz-juelich.de/record/172056
ER  -