The development of new approaches to tuning the resonant magnetic response of simple all‐dielectric nanostructures is very important in modern nanophotonics. Here, it is shown that a resonant magnetic octupole (MOCT) response can be obtained by dividing a solid rectangular silicon block to a quadrumer structure with the introduction of narrow gaps between four nanocubes. The spectral position of the MOCT resonance is controlled and tuned by varying the distance between the nanocubes. It is demonstrated that several magnetic hot‐spots related to the MOCT resonance can be located in the gaps creating a strong magnetic field gradient in free space. It is observed that the resonant excitation of the MOCT moment leads to a significant enhancement of light absorption in the system at the spectral region, where light absorption in bulk silicon is weak. The results of this work can be applied to design new composite antennas and metamaterials based on complex building blocks, energy harvesting devices, and molecular trapping with magnetic hot‐spots.

中文翻译：

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介电四极管的磁八极响应

在现代纳米光子学中，开发用于调整简单全介电纳米结构的共振磁响应的新方法非常重要。在此，通过在四个纳米立方体之间引入狭窄的间隙，将固体矩形硅块划分为方形结构，可以获得共振磁八极（MOCT）响应。通过改变纳米立方体之间的距离来控制和调谐MOCT共振的光谱位置。事实证明，与MOCT共振有关的几个磁性热点可以位于间隙中，从而在自由空间中产生很强的磁场梯度。观察到，MOCT矩的共振激发导致系统中光谱区域的光吸收显着增强，而在该区域中，体硅中的光吸收较弱。