Anisotropic neutron spin resonance in underdoped superconducting ${\mathrm{NaFe}}_{1-x}{\mathrm{Co}}_{x}\mathrm{As}$

Zhang, Chenglin; Song, Yu; Su, Yixi; Kulda, J.; Tan, Guotai; Egami, Takeshi; Sims, Zachary C.; Regnault, L.-P.; Si, Qimiao; Enderle, M.; Dai, Pengcheng

doi:10.1103/PhysRevB.90.140502

Journal Article

FZJ-2014-05605

Anisotropic neutron spin resonance in underdoped superconducting ${\mathrm{NaFe}}_{1-x}{\mathrm{Co}}_{x}\mathrm{As}$

Zhang, C. (Corresponding Author) ; Song, Y. ; Regnault, L.-P. ; Su, Y.FZJ* ; Enderle, M. ; Kulda, J. ; Tan, G. ; Sims, Z. C. ; Egami, T. ; Si, Q. ; Dai, P.

2014
APS College Park, Md.

Physical review / B 90(14), 140502 (2014) [10.1103/PhysRevB.90.140502]

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Please use a persistent id in citations: http://hdl.handle.net/2128/8140 doi:10.1103/PhysRevB.90.140502

Abstract: 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.

Keyword(s): Key Technologies (1st) ; Information Technology and Functional Materials (1st) ; Energy (1st) ; Magnetism (2nd) ; Condensed Matter Physics (2nd)