Pan Bingying, Shen Yao, Hu Die, Feng Yu, Park J T, Christianson A D, Wang Qisi, Hao Yiqing, Wo Hongliang, Yin Zhiping, Maier T A, Zhao Jun
State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China.
Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Garching, D-85748, Germany.
Nat Commun. 2017 Jul 25;8(1):123. doi: 10.1038/s41467-017-00162-x.
Heavily electron-doped iron-selenide high-transition-temperature (high-T ) superconductors, which have no hole Fermi pockets, but have a notably high T , have challenged the prevailing s pairing scenario originally proposed for iron pnictides containing both electron and hole pockets. The microscopic mechanism underlying the enhanced superconductivity in heavily electron-doped iron-selenide remains unclear. Here, we used neutron scattering to study the spin excitations of the heavily electron-doped iron-selenide material LiFeODFeSe (T = 41 K). Our data revealed nearly ring-shaped magnetic resonant excitations surrounding (π, π) at ∼21 meV. As the energy increased, the spin excitations assumed a diamond shape, and they dispersed outward until the energy reached ∼60 meV and then inward at higher energies. The observed energy-dependent momentum structure and twisted dispersion of spin excitations near (π, π) are analogous to those of hole-doped cuprates in several aspects, thus implying that such spin excitations are essential for the remarkably high T in these materials.The microscopic mechanism underlying an enhanced superconductivity in electron-doped iron selenide superconductor remains unclear. Here, Pan et al. report the spin excitations of LiFeODFeSe, revealing analogous momentum structure and dispersion to hole-doped cuprates.
重电子掺杂的铁硒化物高温（高(T_c)）超导体没有空穴费米面，但(T_c)显著较高，这对最初为同时包含电子和空穴口袋的铁基砷化物提出的主流(s)波配对方案构成了挑战。重电子掺杂的铁硒化物中超导电性增强的微观机制仍不清楚。在这里，我们利用中子散射研究了重电子掺杂的铁硒化物材料LiFeODFeSe（(T_c = 41) K）的自旋激发。我们的数据揭示了在约21 meV处围绕((\pi, \pi))的近乎环形的磁共振激发。随着能量增加，自旋激发呈现出菱形，并且它们向外色散，直到能量达到约60 meV，然后在更高能量下向内色散。在((\pi, \pi))附近观察到的自旋激发的能量依赖动量结构和扭曲色散在几个方面类似于空穴掺杂的铜酸盐，因此意味着这种自旋激发对于这些材料中显著高的(T_c)至关重要。电子掺杂的铁硒化物超导体中超导电性增强的微观机制仍不清楚。在这里，潘等人报道了LiFeODFeSe的自旋激发，揭示了与空穴掺杂的铜酸盐类似的动量结构和色散。
