Thickness and Spin Dependence of Raman Modes in Magnetic Layered Fe₃GeTe₂

Abstract 2D layered Fe₃GeTe₂ has attracted increasing attention due to its high magnetic ordering temperature and novel physical properties. Lattice dynamics is a fundamental property of Fe₃GeTe₂, and its relationships with the number of layers and interlayer spin ordering have not yet been explored in depth. Here, by first‐principles density functional theory calculations, the phonon vibrations and Raman intensities of Fe₃GeTe₂ are systematically studied from the bulk to monolayer structures. Furthermore, the spin‐phonon coupling effect is investigated by considering different interlayer magnetic orderings: ferromagnetic and antiferromagnetic. It is found that the frequencies of Raman modes in Fe₃GeTe₂ exhibit considerable dependence on the layer number and spin ordering. The results not only reveal the notable spin‐phonon interactions in Fe₃GeTe₂, but also demonstrate that Raman modes can be utilized for characterizing the sample thickness and interlayer spin ordering in this 2D magnet.