High Energy Spin Excitations in Optimal doped Superconducting BaFe$_{1.9}$ Ni$_{0.1}$As$_{2}$

The recent discovered iron pnictide superconductor which shows a transition temperature up to 50K has drawn much attention in the community. There are indications that superconductivity in the iron arsenides family may be driven by a magnetic pairing mechanism, the nature of which remains poorly understood. In our recent inelastic neutron scattering experiment on optimal doped BaFe$_{1.9}$Ni$_{0.1}$As$_{2}$ sample, spin excitation data are collected throughout the Brillouin zone and up to energy transfer of 400meV which was not probed before. We found that the scattering persists as high as 300 meV in the superconducting sample, and a spectra transfer similar to the parent compound with a spin nematicity was also observed