Lattice Vibration, Raman Modes and Room-Temperature Spin-Phonon Coupling in Intrinsic Two-Dimensional van der Waals Ferromagnetic Fe₃GaTe₂

Two-dimensional (2D) van der Waals (vdW) crystal Fe3GaTe2 with above-room-temperature intrinsic ferromagnetism has attracted widespread attention in spintronics. However, lattice vibrations and spin-phonon coupling in Fe3GaTe2 are still unexplored, and no room-temperature spin-phonon coupling has been identified in 2D vdW magnets. Here, we report two Raman modes with out-of-plane lattice vibrations in Fe3GaTe2: A1g1 and A1g2, whose frequencies increase as the thickness decreases from bulk to 2D, due to the weakening of interlayer vdW interactions and spin exchange coupling. The phonon band dispersions under ferromagnetic and nonmagnetic interlayer spin ordering indicate the existence of spin-phonon coupling. The temperature-dependent phonon frequency of 2D Fe3GaTe2 diverges from the anharmonic model below the Curie temperature, and thus the spin-phonon coupling strengths are ∼0.24–0.28 cm–1 at 300 K, exhibiting the first experimental identification of room-temperature spin-phonon coupling in 2D vdW magnets. This work deepens the understanding of vdW magnets for spintronics at and above room temperature.