Magnetic dynamics of two-dimensional itinerant ferromagnet Fe₃GeTe₂ *

Abstract

Among the layered two-dimensional ferromagnetic materials (2D FMs), due to a relatively high T C , the van der Waals (vdW) Fe 3 GeTe 2 (FGT) crystal is of great importance for investigating its distinct magnetic properties. Here, we have carried out static and dynamic magnetization measurements of the FGT crystal with a Curie temperature T C ≈ 204 K. The M – H hysteresis loops with in-plane and out-of-plane orientations show that FGT has a strong perpendicular magnetic anisotropy with the easy axis along its c -axis. Moreover, we have calculated the uniaxial magnetic anisotropy constant ( K 1 ) from the SQUID measurements. The dynamic magnetic properties of FGT have been probed by utilizing the high sensitivity electron-spin-resonance (ESR) spectrometer at cryogenic temperatures. Based on an approximation of single magnetic domain mode, the K 1 and the effective damping constant ( α eff ) have also been determined from the out-of-plane angular dependence of ferromagnetic resonance (FMR) spectra obtained at the temperature range of 185 K to T C . We have found large magnetic damping with the effective damping constant α eff ∼ 0.58 along with a broad linewidth (Δ H pp > 1000 Oe at 9.48 GHz, H ∥ c -axis). Our results provide useful dynamics information for the development of FGT-based spintronic devices.