[17a-W9_326-1~12] 3.5 Ultrashort-pulse and high-intensity lasers

9:30 AM - 9:45 AM JST(12:30 AM - 12:45 AM UTC)Presentation by Applicant for JSAP Young Scientists Presentation Award

[17a-W9_326-3] Observation of THz emission induced by photo-driven spin currents in magnetic metasurfaces

〇Yuichi Watanabe¹, Hiroshi Watanabe¹, Hidehisa Taketani², Youichi Shiota¹, Shutaro Karube¹, Teruo Ono¹, Masakazu Matsubara², Hideki Hirori¹ (1.Kyoto univ., 2.Osaka univ.)

Keywords:

Ultrafast phenomena,THz spectroscopy,nonlinear optics

To elucidate the mechanism of photo-driven spin current generation in magnetic metasurfaces, we investigated THz emission from Co/Pt multilayers in which a chevron-shaped structure was introduced to break spatial inversion symmetry. By analyzing the dependence of the THz emission amplitude on the polarization angle of the excitation pulse and on magnetization reversal, we demonstrated that spin currents originating from both the structural asymmetry and the magnetization are generated. Furthermore, finite-difference time-domain (FDTD) simulations combined with model calculations revealed that, in the near-field region around the structure, linearly and circularly polarized components are induced and act as driving forces for the magneto-photogalvanic effect. These results clarify the physical origin of ultrafast spin-current generation in magnetic metasurfaces and highlight the crucial role of near-field optical responses in their nonlinear spintronic functionalities.