Chinese Optics Letters

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Magnetically tunable Airy-like magnetostatic surface spin waves

Airy beam, an optical corresponding form of diffraction-free wavepacket solutions of Schrödinger equation, have been found in varieties of optical applications, such as optical trapping, self-bending plasma channels, light bullet generation, light sheet microscopy, and precision machining due to its peculiar properties, e.g., non-diffraction, lateral acceleration, self-bending, and self-healing.

Considering the intrinsic property of waves, Airy-type oscillations have been extended to different kinds of area of wave physics, such as surface plasmons, electron beams, sound waves, and water waves. Particularly, Airy function is the analytic non-diffraction form in 2D space of the Schrödinger equation, which lead to diverse applications in surface waves, such as surface plasmon polaritons (SPPs).

Until now, more physical entities with Airy-type oscillation are being searched. In 2010, one caustic spin wave was introduced theoretically and experimentally. This caustic spin wave related with Airy function but without parabolic profile. This work showed a possibility of generation of Airy-type spin wave.

Spin wave can be considering the propagation of the electron-procession state but not the motion of electrons, in which there is no current forming and avoiding the Joule Heat. The spin wave has been found promising applications in future ultra-high density storage and information processing. Combining the Airy oscillation, an interesting question is whether the Airy-type spin wave can propagate steadily or the propagation of Airy-type spin wave shows parabolic profile.

The generation of Airy-type spin wave in ferromagnetic film was introduced by the research group led by Prof. Haotao Dai from Tianjin University in Chinese Optics Letters Vol. 19, No. 1, 2021 (Haitao Dai, Zolkefl A. Y. Mohamed, Aixiang Xiao, Yongxiang Xue, Ziyang Guo, Yu Zhang, Xiaodong Zhang, Changlong Liu. Magnetically tunable Airy-like beam of magnetostatic surface spin waves [J]. Chinese Optics Letters, 2021, 19(1): 013501). The propagation properties of Airy-type Spin wave was simulated with micromagnetic method.

The schematic of Airy-type Spin Wave

This work developed the 3/2 phase modulation source and formed the parabolic trajectory on the surface of ferromagnetic film. Furthermore, the simulation results also showed that the trajectory of Airy-type spin wave can be tuned with external magnetic field. This modulation effect can also be predicted with theoretical analysis.

Prof. Changlong Liu from Tianjin University appreciates the initial idea of this work, i.e. from the physical essence of the wave, and transplanting the Airy oscillation in spin wave. He believes that this work would lead to either novel applications of Airy oscillation or novel research interests in spin wave.