Polarized inelastic neutron scattering of nonreciprocal spin waves in MnSi
Polarized inelastic neutron scattering of nonreciprocal spin waves in MnSi
复制标题
MnSi 中不可逆自旋波的偏振非弹性中子散射
作者：
Tobias Weber;J. Waizner;Paul Steffens;A. Bauer;C. Pfleiderer;M. Garst;Peter Boni
本文报道了立方手性磁体MnSi中锥形磁螺旋动力学结构因子的自旋极化非弹性中子散射。我们发现自旋翻转散射过程的谱权集中在平行于螺旋轴的单个分支上，这是由中子谱中定义明确的峰推断出来的。相反，对于垂直于螺旋的波矢量转移，谱权分布在磁振子带结构的不同分支之间，这反映在光谱的更宽特征上。考虑到仪器分辨率的影响，我们的实验结果与无参数理论预测在定量上非常一致。而在MnSi中，自旋波的色散在低能量和小磁场下似乎近似互反，相关的自旋分辨谱权显示出明显的非互反，这意味着在零磁场下均匀磁化消失的极限下存在明显的非互反响应。
We report spin-polarized inelastic neutron scattering of the dynamical structure factor of the conical magnetic helix in the cubic chiral magnet MnSi. We find that the spectral weight of spin-flip scattering processes is concentrated on single branches for wavevector transfer parallel to the helix axis as inferred from well-defined peaks in the neutron spectra. In contrast, for wavevector transfers perpendicular to the helix the spectral weight is distributed among different branches of the magnon band structure as reflected in broader features of the spectra. Taking into account the effects of instrumental resolution, our experimental results are in excellent quantitative agreement with parameter-free theoretical predictions. Whereas the dispersion of the spin waves in MnSi appears to be approximately reciprocal at low energies and small applied fields, the associated spin-resolved spectral weight displays a pronounced non-reciprocity that implies a distinct non-reciprocal response in the limit of vanishing uniform magnetization at zero magnetic field.