Combining the vector diffraction theory with the inverse Faraday effect, we have theoretically studied magnetization shaping generated by tight focusing of an azimuthally polarized multi-Gaussian beam superimposed with a helical phase. By selecting optimized parameters of a multi-Gaussian beam and topological charge of a spiral phase plate, not only a super-long and sub-wavelength longitudinal magnetization needle with single/dual channels for a single-lens high numerical aperture focusing system, but also an extra-long and three-dimensional super-resolution longitudinal magnetization chain with single/dual channels for a 4π high numerical aperture focusing system is achieved in the focal region. Furthermore, by continuously changing the phase difference between two counter-propagating beams, these super-long longitudinal magnetization chains with three-dimensional super-resolution can dynamically move along the z-axis. It is expected that these results pave the path for fabricating magnetic lattices for spin wave operation, multiple atoms or magnetic particle trapping and transportation, confocal and magnetic resonance microscopy, as well as multilayer ultrahigh density magnetic storage.

No abstract

The interplay between light and magnetism is considered as a promising solution to fully steer multidimensional magnetic oscillations/vectors, facilitating the development of all-optical multilevel recording/memory technologies. To date, impressive progress in multistate magnetization instead of a binary level has been witnessed by primarily resorting to double laser beam excitation. Yet, the control mechanisms are limited to specific magnetic medium or intricate optical configuration as well as overlooking the crystallographic architecture of the media and the polarization-phase linkage of the light fields. Here, we theoretically present a novel all-optical strategy for generating arbitrary multistate magnetization through the inverse Faraday effect. This is achieved by strongly focusing a single vortex-phase configured beam with circular polarization onto the anisotropic magnetic medium. By judiciously tuning the topological charge effect, the optical anisotropic effect, and the anisotropic optomagnetic effect, the light-induced magnetic vector can be flexibly redistributed between its transverse and longitudinal components, thus enabling orientation-unlimited multilevel magnetization control. In this optomagnetic process, we also reveal the role of anisotropy-mediated spin-orbit coupling, another physical mechanism that enables the effective translation of the angular momentum of light fields to the magnetic system. Furthermore, the conceptual paradigm of all-optical multistate magnetization is verified. Our findings show great prospect in multidimensional high-density optomagnetic recording and memory devices and also in high-speed information processing science and technology.

In this work, we present a feasible pathway for initially constructing light-induced isotropic super-resolved magnetization along with steerable orientations and trivial side-lobe levels. Toward this end, the counter-propagating azimuthally polarized vortex Hermite–Gauss beams are tailored with angular rotators at the exit pupil planes and then focused by using high numerical aperture objective lenses in a 4π optical microscopic configuration. By wilfully regulating the rotatable azimuth angle and judiciously optimizing the scaling parameter, the spherical super-resolved (λ3/24), orientation-tunable (any direction), and sidelobe-negligible (<20%) magnetization spot can thus be produced. Such well-defined magnetization behavior is attributed to not merely the axially symmetrical destruction of the incoming vectorial fields but also the constructive interference in all directions caused by all the magnetization components. The demonstrated outcomes hold great potential in developing novel magneto-optical and spin-photonic devices.