Reciprocal excitation of propagating spin-waves by a laser pulse and their reciprocal mapping in magnetic metal films
Reciprocal excitation of propagating spin-waves by a laser pulse and their reciprocal mapping in magnetic metal films
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激光脉冲传播自旋波的相互激发及其在磁性金属薄膜中的相互映射
DOI：
10.1103/physrevb.96.014438
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发表时间：
2017
影响因子：
3.7
通讯作者：
and S. Mizukami
中科院分区：
文献类型：
--
作者：
A. Kamimaki;S. Iihama;Y. Sasaki;Y. Ando;and S. Mizukami
利用全光时空分辨磁光克尔效应显微镜研究了20 nm厚坡莫合金薄膜中聚焦脉冲激光诱导的静磁表面自旋波（MSSW）的传播，以阐明MSSW发射的互易性和对称性.显微镜设置构造与可变方向的施加磁场，并相应的角度依赖性进行了检查。MSSW是从激光光斑中发射的，与天线方法获得的非互易发射相反。具体而言，所观察到的激励振幅和相位在实验误差内与传播和磁化方向无关。通过将数据转换到波数-频率空间，MSSW色散关系在波数为2-3 rad/和频率为10 GHz的范围内被清楚地识别。这些观察结果与聚焦激光光斑内的面外形状磁各向异性的超快调制模型是一致的。除了证实激光诱导MSSW的对称和互易发射外，该研究还表明该技术可以提供金属中MSSW的全光学显微光谱，例如布里渊光散射技术。
Focused pulse-laser-induced propagating magnetostatic surface spin waves (MSSWs) were investigated using an all-optical space-time-resolved magneto-optical Kerr effect microscope in 20-nm-thick permalloy thin films to clarify reciprocity and symmetry of MSSW emission. The microscope setup was constructed with variable direction of the applied magnetic field, and the corresponding angular dependence was examined. MSSWs were reciprocally emitted from the laser spot, in contrast to the nonreciprocal emission obtained by the antenna method. Specifically, the observed excitation amplitude and phase were independent of the propagation and magnetization directions within experimental error. By transforming the data into wave number–frequency space, the MSSW dispersion relation was clearly identified within the wave number of 2–3 rad/and frequency of 10 GHz. These observations are consistent with the model of ultrafast modulation of out-of-plane shape magnetic anisotropy inside the focused laser spot. In addition to confirming the symmetric and reciprocal emission of laser-induced MSSWs, the study demonstrated that this technique can provide all-optical microscopic spectroscopy for MSSW in metals, such as Brillouin light-scattering technique.