Using analysis of isofrequency contours of the spin-wave dispersion relation, supported by micromagnetic simulations, we study the propagation of spin-wave (SW) beams in thin ferromagnetic films through the areas of the inhomogeneous refractive index. We compare the transmission and reflection of SWs in areas with gradual and step variation of the SW refractive index. In particular, we show the mirage effect for SWs with narrowing SW beam width and an application of the gradual modulation of the SWs refractive index as a diverging lens. Furthermore, we study the propagation of SWs in ferromagnetic stripe with modulated refractive index. We demonstrate that the system can be considered as the graded-index waveguide, which preserves the width of the SW beam for a long distance—the property essential for prospective applications of magnonics.

中文翻译：

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自旋光束在具有梯度折射率的铁磁薄膜中的传播：幻影效应和预期应用

在微磁模拟的支持下，使用自旋波色散关系的等频轮廓分析，我们研究了自旋波（SW）束在薄铁磁薄膜中通过非均匀折射率区域的传播。我们将SW的透射率和反射率随SW折射率的逐渐变化和阶跃变化进行比较。特别是，我们展示了具有更窄的SW光束宽度的SW的幻影效果，以及SW折射率的逐渐调制作为发散透镜的应用。此外，我们研究了在具有调制折射率的铁磁条中SW的传播。我们证明了该系统可以看作是渐变折射率波导，它可以在很长的距离内保留西南光束的宽度，这对于准磁子学的未来应用至关重要。