Sub-THz High Spin Precession Frequency in van der Waals Ferromagnet Fe₃GaTe₂

The 2D magnet Fe₃GaTe₂ has received considerable attention for its high Curie temperature (T_C), robust intrinsic ferromagnetism, and significant perpendicular magnetic anisotropy (PMA). In this study, the dynamic magnetic properties of Fe₃GaTe₂ are systematically investigated using an all-optical pump-probe technique. We find that the spin precession frequency (f) is as high as 351.2 GHz at T = 10 K under a field of H = 70 kOe. However, it decreases to 242.8 GHz at 300 K, mainly due to the reduced effective PMA field (H_keff). The Gilbert damping factor (α) is modest, which increases from 0.039 (10 K) to 0.075 (300 K) owing to the enhanced scattering rate. Interestingly, when Fe₃GaTe₂ is coupled with 2 nm of Co, the H_keff, f, and α just decrease slightly, highlighting the dominant influence of Fe₃GaTe₂. These findings substantially deepen our understanding of Fe₃GaTe₂, promoting the development of spintronic devices based on advanced 2D magnetic materials.