Ferrimagnetic ground state in Fe3GaTe2 and its influence on its skyrmions.

The recently discovered layered ferromagnet Fe3GaTe2 is attracting significant attention due to its high Curie temperature, low dimensionality, and the presence of topological spin textures even above room temperature, which makes Fe3GaTe2 a good candidate for applications in spintronics. However, a precise determination of its magnetic ground state and an understand of the mechanisms stabilizing skyrmions is essential. We found that Fe3GaTe2 displays a metastable ferromagnetic (FM) state but a stable ferrimagnetic (FiM) ground state, and no glassiness as claimed for sister compounds. Evidence for a topological Hall effect and skyrmions are observed at the boundary between FM and FiM phases according to magnetic force microscospy, implying that competing magnetic interactions play a crucial role in their formation. Furthermore, we found a coincidence between the thermal hysteresis observed in the magnetization, that is associated with the competition between FM and FiM phases, and thermal hysteresis in the skyrmion density measured through Lorentz transmission electron microscopy. AC magnetic susceptibility, singe-crystal X-ray diffraction, and high-resolution transmission electron microscopy images will be discussed in an attempt to correlate the presence of spin textures with the actual crystal structure.