Spin–Phonon Interactions and Anharmonic Lattice Dynamics in Fe3GeTe2

• Published in: Advanced Physics Research Vol. 2; no. 8
• Main Authors: Cai, Qingan, Zhang, Yuemei, Luong, Diana, Tulk, Christopher A., Fokwa, Boniface P.T., Li, Chen
• Format: Journal Article
• Language: English
• Published: Edinburgh John Wiley & Sons, Inc 01.08.2023; Wiley-VCH
• Subjects: Anharmonic Lattice Dynamics; Anharmonicity; Approximation; Density functional theory; DFT calculations; Electrons; Lattice vibration; Magnetic properties; Magnetic thin films; Phase transitions; Phonons; Pressure dependence; Pressure effects; Raman spectra; Softening; Spectrum analysis; Spin dynamics; Spin exchange; Spin-orbit interactions; Spintronic materials, Fe3GeTe2; Spin‐Phonon Interactions; Stiffening; Temperature dependence; Temperature effects
• ISSN: 2751-1200; 2751-1200
• DOI: 10.1002/apxr.202200089

Raman scattering is performed on Fe3GeTe2 (FGT) at temperatures from 8 to 300 K and under pressures from the ambient pressure to 9.43 GPa. Temperature‐dependent and pressure‐dependent Raman spectra are reported. The results reveal respective anomalous softening and moderate stiffening of the two Raman active modes as a result of the increase of pressure. The anomalous softening suggests anharmonic phonon dynamics and strong spin–phonon coupling. Pressure‐dependent density functional theory and phonon calculations are conducted and used to study the magnetic properties of FGT and assign the observed Raman modes, E2g2$E_{2{\rm{g}}}^2$ and A1g1$A_{1{\rm{g}}}^1$. The calculations proved the strong spin–phonon coupling for the E2g2$E_{2{\rm{g}}}^2$ mode. In addition, a synergistic interplay of pressure‐induced reduction of spin exchange interactions and spin–orbit coupling effect accounts for the softening of the E2g2$E_{2{\rm{g}}}^2$ mode as pressure increases. Temperature‐ and pressure‐dependent Raman scattering measurements on Fe3GeTe2 reveal anomalous softening and moderate stiffening of the E2g2${E}_{2g}^{2}$ and A1g1${A}_{1g}^{1}$ Raman active modes, respectively, as pressure increases. The anomalous softening of the E2g2${E}_{2g}^{2}$ mode suggests anharmonic phonon dynamics and strong spin–phonon coupling, which is approved by density functional theory and phonon calculations.