Giant magneto-optical effect in van der Waals room temperature ferromagnet Fe₃GaTe₂

Abstract The discovery of ferromagnetic two-dimensional (2D) van der Waals (vdWs) materials provides an opportunity to explore intriguing physics and develop innovative spin electronic devices. However, the main challenge for practical applications of vdWs ferromagnetic crystals lies in the weak intrinsic ferromagnetism and small perpendicular magnetic anisotropy (PMA) above room temperature. Here, we report the intrinsic vdWs ferromagnetic crystal Fe3GaTe2, synthesized by the self-flux method, exhibiting a Curie temperature (TC) of 370 K, a high saturation magnetization of 33.47 emu/g, and a large PMA energy density of approximately 4.17 × 105 J/m3. Furthermore, for the first time, the magneto-optical effect has been systematically investigated in Fe3GaTe2. The doubly degenerate E2g(Γ) mode reverses the helicity of incident photons, indicating the existence of pseudoangular momentum (PAM) and chirality. Meanwhile, the non-degenerate non-chiral A1g(Γ) phonon exhibits a significant magneto-Raman effect under an external out-of-plane magnetic field. These results lay the groundwork for studying phonon chirality and magneto-optical phenomena in 2D magnetic materials, providing the feasibility for further fundamental research and application in spintronic devices.