National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan.
Phys Rev Lett. 2011 Feb 11;106(6):067003. doi: 10.1103/PhysRevLett.106.067003.
A neutron scattering study of heavily hole-overdoped superconducting KFe2As2 revealed a well-defined low-energy incommensurate spin fluctuation at [π(1 ± 2 δ),0] with δ = 0.16. The incommensurate structure differs from the previously observed commensurate peaks in electron-doped AFe2As2 (A = Ba, Ca, or Sr) at low energies. The direction of the peak splitting is perpendicular to that observed in Fe(Te,Se) or in Ba(Fe,Co)2As2 at high energies. A band structure calculation suggests interband scattering between bands around the Γ and X points as an origin of this incommensurate peak. The perpendicular direction of the peak splitting can be understood within the framework of multiorbital band structure. The results suggest that spin fluctuation is more robust in hole-doped than in electron-doped samples, which can be responsible for the appearance of superconductivity in the heavily hole-doped samples.
一项针对重度空穴掺杂超导 KFe2As2 的中子散射研究表明，在[π(1 ± 2 δ),0]处存在一个明确定义的低能非共线自旋涨落，其中 δ = 0.16。该非共线结构与之前在电子掺杂 AFe2As2（A = Ba、Ca 或 Sr）中观察到的低能共线峰不同。峰分裂的方向与在 Fe(Te,Se)或 Ba(Fe,Co)2As2 中在高能下观察到的方向垂直。能带结构计算表明，Γ 和 X 点附近能带之间的能带散射是这种非共线峰的起源。在多轨道能带结构的框架内，可以理解峰分裂的垂直方向。研究结果表明，自旋涨落在空穴掺杂样品中比在电子掺杂样品中更为稳健，这可能是在重度空穴掺杂样品中出现超导性的原因。
