Anisotropic magnetization dynamics in Fe5GeTe2 at room temperature

TL;DR

This study investigates the anisotropic magnetization dynamics of Fe5GeTe2 at room temperature using broadband ferromagnetic resonance, revealing unexpected isotropy in damping and anisotropic g-factor behavior related to spin fluctuations.

Contribution

It provides the first experimental analysis of anisotropic magnetization damping and g-factor in Fe5GeTe2 at room temperature, challenging ab-initio predictions.

Findings

No intrinsic anisotropy in magnetization damping observed.

Significant anisotropy in Lande's g factor near room temperature.

Damping appears unaffected by spin-orbit interactions.

Abstract

The determination of Lande's g-factor and the damping constant is central to extracting crucial information about the spin-spin and spin-orbit interactions in magnetically ordered systems. In insulating compounds based on 3d elements, the spin-orbit interaction can be effectively probed by investigating the ground state of the corresponding free 3d ion within the crystalline environment. For metallic systems, the problem is non-trivial because of additional band structure effects. Here, we investigate the anisotropic magnetization dynamics in bulk single crystalline Fe5GeTe2, a van der Waals 2D itinerant ferromagnet at room temperature, using broadband ferromagnetic resonance spectroscopy. Strikingly, contrary to the results of ab-initio calculations, we do not observe any intrinsic anisotropy of magnetization damping close to room temperature, suggesting diminished role of spin-orbit interaction. However, there is a sizable anisotropy in the Lande's g factor near room temperature which is attributed to anisotropic critical spin fluctuations.