Lattice Dynamics and Phonon Dispersion of the van der Waals Layered Ferromagnet Fe₃GaTe₂.

Abstract

Despite the tremendous progress in spintronic studies of the van der Waals (vdW) room-temperature ferromagnet Fe₃GaTe₂, much less effort has been spent on studying its lattice dynamics and possible interaction with spintronic degrees of freedom. In this work, by combining Raman spectroscopy in a wide range of pressures (atmospheric pressure ∼19.5 GPa) and temperature (80-690 K) with first-principles calculations, we systematically studied the lattice dynamics and phonon dispersion of Fe₃GaTe₂. Our results show that the phonon energies of Fe₃GaTe₂ located at 126.0 and 143.5 cm^-1 originate from the anharmonic <i>E</i>_2<i>g</i>² and harmonic <i>A</i>_1<i>g</i>¹ vibration modes, respectively. Furthermore, the first room-temperature spin-phonon coupling in the vdW ferromagnet is observed with a strength of ∼0.81 cm^-1 at 300 K, by identifying Raman anomalies in both phonon energy and full width at half-maximum of <i>E</i>_2<i>g</i>² below the Curie temperature of Fe₃GaTe₂. Our findings are valuable for fundamental and applied studies of vdW materials under variable conditions.