Gallardo Rodolfo A, Alvarado-Seguel Pablo, Brevis Felipe, Roldán-Molina Alejandro, Lenz Kilian, Lindner Jürgen, Landeros Pedro
Departamento de Física, Universidad Técnica Federico Santa María, Avenida España 1680, Valparaíso 2390123, Chile.
Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Santiago 9170124, Chile.
Nanomaterials (Basel). 2022 Aug 14;12(16):2785. doi: 10.3390/nano12162785.
Magnetization-graded ferromagnetic nanostrips are proposed as potential prospects to channel spin waves. Here, a controlled reduction of the saturation magnetization enables the localization of the propagating magnetic excitations in the same way that light is controlled in an optical fiber with a varying refraction index. The theoretical approach is based on the dynamic matrix method, where the magnetic nanostrip is divided into small sub-strips. The dipolar and exchange interactions between sub-strips have been considered to reproduce the spin-wave dynamics of the magnonic fiber. The transition from one strip to an infinite thin film is presented for the Damon-Eshbach geometry, where the nature of the spin-wave modes is discussed. An in-depth analysis of the spin-wave transport as a function of the saturation magnetization profile is provided. It is predicted that it is feasible to induce a remarkable channeling of the spin waves along the zones with a reduced saturation magnetization, even when such a reduction is tiny. The results are compared with micromagnetic simulations, where a good agreement is observed between both methods. The findings have relevance for envisioned future spin-wave-based magnonic devices operating at the nanometer scale.
磁化梯度铁磁纳米带被认为是引导自旋波的潜在前景。在这里，饱和磁化强度的可控降低能够使传播的磁激发局域化，其方式类似于在具有变化折射率的光纤中控制光。理论方法基于动态矩阵法，其中磁纳米带被划分为小的子带。考虑了子带之间的偶极和交换相互作用，以再现磁子纤维的自旋波动力学。对于达蒙 - 埃施巴赫几何结构，给出了从一个条带到无限薄膜的转变，其中讨论了自旋波模式的性质。提供了对作为饱和磁化强度分布函数的自旋波输运的深入分析。据预测，即使饱和磁化强度的降低很小，沿饱和磁化强度降低的区域诱导自旋波的显著通道化也是可行的。将结果与微磁模拟进行了比较，两种方法之间观察到了良好的一致性。这些发现对于设想的未来在纳米尺度运行的基于自旋波的磁子器件具有相关性。
