Electronic and vibrational properties of bulk Cr2Ge2Te6 from first-principles calculations

We use density functional theory based ab initio calculations to investigate the structural, vibrational, magnetic, and electronic properties of the layered ferromagnet Cr2Ge2Te6 (CGT) that has attracted attention for potential spintronic applications. We optimize the structure for a fixed c/a ratio. Our results are in excellent agreement with experimental data on structure, phonons, and electronic properties. The use of van der Waals interactions and relativistic spin-orbit coupling yields accurate lattice constants and interlayer distances. Simultaneously, the adopted theoretical methods lead to a rigorous description of the vibrational normal modes, as well as the valence bands, that are in excellent agreement with Raman spectroscopy and angle-resolved photoemission spectroscopy spectra, respectively. The magnetic moment is slightly overestimated, and the magnetic anisotropy has the correct sign but is greater in magnitude than that in experiment. We find that inclusion of the on-site Coulomb repulsion on Cr-3d orbitals worsens agreement with experiment, in contrast to previous studies. Our results provide a path toward ab initio analysis of magnetic heterostructures based on CGT.