We present an all-optical scheme for the generation of longitudinal magnetization superoscillation based on the vectorial diffraction theory and the inverse Faraday effect. To achieve this, an azimuthally polarized high-order Laguerre–Gaussian vortex mode is firstly focused by a high numerical aperture (NA) objective and then impinges on an isotropic magneto-optical material. It is found that, by judiciously controlling the intrinsic arguments (radial mode index (p) and truncation parameter (β)) of such a configurable vectorial vortex beam, the longitudinal magnetic domain induced in the focal plane can be switched from a peak sub-wavelength magnetization (> 0.36λ/NA), via the fastest Fourier magnetization component (∼0.36λ/NA), to a super-oscillation magnetization hotspot (< 0.36λ/NA). We further examine the dependence of the transverse size, the side lobe, and the energy conversion efficiency within the focal magnetization domain on both the p and β of the initial vortex modes, confirming that the higher-order structured vortex beams are preferable alternatives to trigger robust longitudinal magnetization superoscillation. In addition, the underlying mechanisms behind the well-defined magnetization phenomena are unveiled. The ultra-small-scale longitudinal magnetization demonstrated here may hold massive potential applications in high-density all-optical magnetic recording/storage, super-resolution magnetic resonance imaging, atom trapping and spintronics.

中文翻译：

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由高阶方位极化拉盖尔-高斯涡旋模式实现的纵向磁化超振荡

我们提出了一种基于矢量衍射理论和反法拉第效应产生纵向磁化超振荡的全光学方案。为了实现这一点，方位极化的高阶拉盖尔-高斯涡旋模式首先由高数值孔径 (NA) 物镜聚焦，然后撞击各向同性磁光材料。发现，通过明智地控制这种可配置矢量涡旋光束的内在参数（径向模式指数（p）和截断参数（β）），焦平面中感应的纵向磁畴可以从峰值亚波长磁化（> 0.36 λ /NA），通过最快的傅立叶磁化分量（~0.36 λ/NA)，到超振荡磁化热点 (< 0.36 λ /NA)。我们进一步检查了焦磁化域内的横向尺寸、旁瓣和能量转换效率对初始涡流模式的p和β的依赖性，确认高阶结构涡流束是触发的优选替代方案强大的纵向磁化超振荡。此外，揭示了明确定义的磁化现象背后的潜在机制。这里展示的超小尺度纵向磁化可能在高密度全光磁记录/存储、超分辨率磁共振成像、原子俘获和自旋电子学方面具有巨大的潜在应用。