[Lipscombe, OJ; Harriger, LW; Zhang, CL; Wang, MY; Egami, T; Dai, PC] Univ Tennessee, Dept Phys & Astron, Knoxville, TN 37996 USA; [Freeman, PG; Enderle, M] Inst Laue Langevin, F-38042 Grenoble 9, France; [Egami, T] Univ Tennessee, Dept Mat Sci & Engn, Knoxville, TN 37996 USA; [Egami, T; Dai, PC] Oak Ridge Natl Lab, Oak Ridge, TN 37831 USA; [Hu, JP] Purdue Univ, Dept Phys, W Lafayette, IN 47907 USA; [Hu, JP; Xiang, T; Dai, PC] Chinese Acad Sci, Inst Phys, Beijing 100190, Peoples R China; [Xiang, T] Chinese Acad Sci, Inst Theoret Phys, Beijing 100190, Peoples R China; [Norman, MR] Argonne Natl Lab, Div Mat Sci, Argonne, IL 60439 USA
英文摘要:
We use polarized inelastic neutron scattering to show that the neutron spin resonance below T(c) in superconducting BaFe(1.9)Ni(0.1)As(2) (T(c)= 20 K) is purely magnetic in origin. Our analysis further reveals that the resonance peak near 7 meV only occurs for the planar response. This challenges the common perception that the spin resonance in the pnictides is an isotropic triplet excited state of the singlet Cooper pairs, as our results imply that only the S(001)= +/- 1 components of the triplet are involved.
