Layer breathing Raman mode in two-dimensional van der Waals magnet Cr2Ge2Te6.

Abstract

We report the observation of a weak broad mode with characteristic dependence on thickness of flakes suggesting this as a layer breathing (LB) mode in(CGT) measured using Raman spectroscopy. Symmetry analysis confirms that the CGT falls under the non-polar category of layered material. The evolution of the LB mode frequency with increasing layer number () reveals a distinct softening trend, characteristic of weakening restoring forces in thicker flakes. By fitting the experimental Raman data using the linear chain model (LCM), we quantitatively extract the interlayer force constant (), providing a measure of the vdW coupling strength between layers. The good agreement between experimental and theoretical results establishes the LCM as a reliable framework for describing interlayer phonon dynamics in CGT. In conclusion, these findings not only deepen our understanding of interlayer interactions and symmetry-driven phonon behavior but also offer a powerful diagnostic for assuming layer thickness and structural integrity in vdW magnets. Such insights are pivotal for 2D spintronics and multifunctional device architectures based on CGT.