Magnetic properties of ferromagnetic nanoparticles of Fe _x GeTe₂ (x = 3, 5) directly exfoliated and dispersed in pure water

Abstract

FexGeTe2 (x = 3, 5) are two-dimensional ferromagnetic materials that have gained significant attention from researchers due to their relatively high curie temperature and tunability. However, the methods for preparing ferromagnetic nanoparticles and large-area FexGeTe2 films are still in the early stages. Here, we studied the magnetic properties of FexGeTe2 ferromagnetic nanoparticles exfoliated via wet exfoliation in pure water. The coercive field of Fe3GeTe2 ferromagnetic nanoparticles increases significantly, up to 60 times, while that of Fe5GeTe2 only slightly increases from that of bulk crystals. Further investigation related to the dimension of nanoparticles and the Henkel plot analysis reveals that the variation in their coercive field stems from the material's thickness-dependent coercive field and the type of term that governs the interaction between single-domain nanoparticles. Our work demonstrates a facile method for preparing ferromagnetic nanoparticles using van der Waals ferromagnetic materials and tuning their magnetic properties.