Anisotropic electron-phonon coupling and chiral phonons in van der Waals room temperature ferromagnet Fe${}_5$GeTe${}_2$

Abstract

The layered van der Waals Fe${}_5$GeTe${}_2$ (F5GT) compound exhibits room-temperature ferromagnetism, making it a promising candidate for technological applications. In our study, combined temperature, wavelength, and polarization-dependent Raman measurements, along with {\it ab initio} calculations reveal important aspects of lattice dynamics and electron-phonon interactions. The angle-resolved Raman intensity under linear polarization configurations exhibits a strong tilt in the laboratory coordinate system, indicating the existence of anisotropic electron-phonon coupling. The temperature evolution of this anisotropy is discussed by extracting the phase factor of the Raman tensor elements from the angle-resolved intensity measured at different temperatures, also uncovering a spin-orbit coupling-mediated electron-phonon response in F5GT. The thermal evolution of electron-phonon coupling is also examined by measuring the temperature dependence of the Fano parameter of the asymmetric peak in the Raman spectra, while wavelength-dependent measurements establish the role of optical resonance in enhancing the anisotropic interaction. Finally, the threefold rotational symmetry guarantees the existence of chiral phonons. We present direct spectroscopic evidence for these chiral vibrational modes through cross-circularly polarized Raman measurements, complemented by theoretical calculations of phonon circular polarization. Together, these results identify F5GT as an ideal platform for investigating emergent couplings among lattice, electronic, and magnetic degrees of freedom and for advancing the understanding of chiral phonons in magnetic van der Waals materials.

Main text: 13 pages, 6 figures + Supplemental Material: 14 pages, 14 figures

References in corpus (21)

• 2D materials and van der Waals heterostructures
• Quantum ESPRESSO toward the exascale
• Implementation strategies in phonopy and phono3py
• Van der Waals heterostructures for spintronics and opto-spintronics
• Truly chiral phonons in α-HgS
• Tuning Magnetic Order in the van der Waals Metal Fe5GeTe2 by Cobalt Substitution
• Current-induced deterministic switching of van der Waals ferromagnet at room temperature
• Skyrmionic Spin Structures in Layered Fe5GeTe2 Up To Room Temperature
• Chiral phonons: circularly polarized Raman spectroscopy and $\text{ab initio}$ calculations in a chiral crystal tellurium
• Strong magneto-optical and anomalous transport manifestations in two-dimensional van der Waals magnets Fe${}_n$GeTe${}_2$ ($n$ = 3, 4, 5)
• Weyl phonons in chiral crystals
• Lattice dynamics and phase transitions in Fe${}_{3-x}$GeTe${}_2$
• Magnetic order induced chiral phonons in a ferromagnetic Weyl semimetal
• QERaman: An open-source program for calculating resonance Raman spectra based on Quantum ESPRESSO
• Selective observation of enantiomeric chiral phonons in $\alpha$-quartz
• Lattice dynamics in chiral tellurium by linear and circularly polarized Raman spectroscopy: crystal orientation and handedness
• Tuning the Room Temperature Ferromagnetism in Fe5GeTe2 by Arsenic Substitution
• Dynamical properties of magnetic topological insulator $T$Bi${}_2$Te${}_4$ ($T=$Mn, Fe): phonons dispersion, Raman active modes, and chiral phonons study
• Thermal cycling induced alteration of the stacking order and spin-flip in the room temperature van der Waals magnet Fe${}_5$GeTe${}_2$
• Anisotropic magnetization dynamics in Fe5GeTe2 at room temperature
• Writing and detecting topological charges in exfoliated Fe${}_{5-x}$GeTe${}_2$