Controlled light-induced longitudinal magnetization spots with opposite directions

Tailoring the magnetic field induced by the inverse Faraday effect has received much attention due to their potential applications in data storage. However, much issues remains, hindering the application of all-optical magnetic storage technology, e. g, the challenges in the speed and precision of recording and deleting different bits of information in different positions of the magnetic recording film. To achieve on-the-fly magnetic recording and deleting of information with a high degree of accuracy, pure longitudinal magnetization spots with opposite directions are theoretically produced in this paper. Firstly, twin pure longitudinal magnetization spots with opposite directions are induced by tailoring the amplitude and phase of a tightly focused azimuthally polarized beam (APB). These pure longitudinal magnetization spots with opposite directions opens a route for writing and deleting recording bits with high writing speed as well as high degree of accuracy. Then we proved that this strategy can also be used to generate multiple longitudinal magnetization spots with opposite directions, which will facilitate the high-density 3D optomagnetic recording. Compared with traditional methods, which require complex optical systems to generate longitudinal magnetization spots with opposite directions, we only need to tailor the amplitude and phase of the APB. More importantly, the directions of the induced magnetization spots can be tuned easily, and the magnetization spots have the same intensity distribution.