摘要
We report an inelastic neutron scattering investigation on the spin resonance mode in the optimally hole-doped ironbased superconductor Ba_(0.67)K_(0.33)Fe_(2)As_(2)with T_c=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.
作者
Tao Xie
Chang Liu
Tom Fennell
Uwe Stuhr
Shi-Liang Li
Hui-Qian Luo
谢涛;刘畅;Tom Fennell;Uwe Stuhr;李世亮;罗会仟(Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;School of Physical Sciences,University of Chinese Academy of Sciences,Beijing 100190,China;Laboratory for Neutron Scattering and Imaging,Paul Scherrer Institut,CH-5232 Villigen PSI,Switzerland;Songshan Lake Materials Laboratory,Dongguan 523808,China)
基金
Project supported by the National Key Research and Development Program of China(Grant Nos.2018YFA0704200,2018YFA0305602,2017YFA0303100,2017YFA0302900)
the National Natural Science Foundation of China(Grant Nos.11822411 and 11961160699)
the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(CAS)(Grant Nos.XDB25000000 and XDB07020300)
K.C.Wong Education Foundation(Grant No.GJTD-2020-01)
the Youth Innovation Promotion Association of CAS(Grant No.Y202001)
the Beijing Natural Science Foundation,China(Grant No.JQ19002)。
