%A Tao Xie(谢涛), Chang Liu(刘畅), Tom Fennell, Uwe Stuhr, Shi-Liang Li(李世亮), and Hui-Qian Luo(罗会仟) %T Dispersion of neutron spin resonance mode in Ba0.67K0.33Fe2As2 %0 Journal Article %D 2021 %J Chin. Phys. B %R 10.1088/1674-1056/ac3651 %P 127402-127402 %V 30 %N 12 %U {https://cpb.iphy.ac.cn/CN/abstract/article_124209.shtml} %8 2021-11-15 %X We report an inelastic neutron scattering investigation on the spin resonance mode in the optimally hole-doped iron-based superconductor Ba0.67K0.33Fe2As2 with Tc=38.2 K. Although the resonance is nearly two-dimensional with peak energy ER≈14 meV, it splits into two incommensurate peaks along the longitudinal direction ([H, 0, 0]) and shows an upward dispersion persisting to 26 meV. Such dispersion breaks through the limit of total superconducting gaps tot=|k|+|k+Q|(about 11-17 meV) on nested Fermi surfaces measured by high resolution angle resolved photoemission spectroscopy (ARPES). These results cannot be fully understood by the magnetic exciton scenario under s±-pairing symmetry of superconductivity, and suggest that the spin resonance may not be restricted by the superconducting gaps in the multi-band systems.