Magnetic dynamics of two-dimensional itinerant ferromagnet Fe3GeTe2 * *Project supported by the National Key Research and Development Program of China (Grant No. 2016YFA0300803), the National Natural Science Foundation of China (Grant Nos. 11774150, 12074178, 61427812, 11774160, 61805116, and 61271077), and the Natural Science Foundation of Jiangsu Province of China (Grant Nos. BK20192006, BK20180056, and BK20200307).

Abstract

Among the layered two-dimensional ferromagnetic materials (2D FMs), due to a relatively high T C, the van der Waals (vdW) Fe3GeTe2 (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.