Recent work has shown that optical magnetism, generally considered a challenging light–matter interaction, can be significant at the nanoscale. In particular, the dielectric nanostructures that support magnetic Mie resonances are low-loss and versatile optical magnetic elements that can effectively manipulate the magnetic field of light. However, the narrow magnetic resonance band of dielectric Mie resonators is often overshadowed by the electric response, which prohibits the use of such nanoresonators as efficient magnetic nanoantennas. Here, we design and fabricate a silicon (Si) truncated cone magnetic Mie resonator at visible frequencies and excite the magnetic mode exclusively by a tightly focused azimuthally polarized beam. We use photoinduced force microscopy to experimentally characterize the local electric near-field distribution in the immediate vicinity of the Si truncated cone at the nanoscale and then create an analytical model of such structure that exhibits a matching electric field distribution. We use this model to interpret the PiFM measurement that visualizes the electric near-field profile of the Si truncated cone with a superior signal-to-noise ratio and infer the magnetic response of the Si truncated cone at the beam singularity. Finally, we perform a multipole analysis to quantitatively present the dominance of the magnetic dipole moment contribution compared to other multipole contributions into the total scattered power of the proposed structure. This work demonstrates the excellent efficiency and simplicity of our method of using Si truncated cone structure under APB illumination compared to other approaches to achieve dominant magnetic excitations.

中文翻译：

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纳米Mie谐振器中通过结构化光照明实现的独家磁激励

最近的研究表明，通常被认为是具有挑战性的光-物质相互作用的光磁在纳米尺度上可能非常重要。特别地，支持磁共振米氏共振的介电纳米结构是可以有效地操纵光的磁场的低损耗且用途广泛的光学磁性元件。但是，电介质三重谐振器的狭窄的磁共振带常常被电响应所掩盖，这阻止了将这种纳米谐振器用作有效的磁性纳米天线。在这里，我们设计并制造了可见光频率下的硅（Si）截头圆锥形磁Mie谐振器，并且仅通过紧密聚焦的方位极化光束来激发磁模式。我们使用光致感应力显微镜在纳米尺度上以实验的方式表征了Si截锥的紧邻区域中的局部电近场分布，然后创建了具有匹配电场分布的这种结构的分析模型。我们使用该模型来解释PiFM测量，该测量以极好的信噪比可视化Si截锥的电近场轮廓，并推断出光束奇异性时Si截锥的磁响应。最后，我们进行了一个多极分析，定量地提出了磁偶极矩贡献相对于其他多极贡献在拟议结构总散射功率中的支配地位。