Magnetic properties of amorphous low-temperature iron germanium films

The emergence of topological magnetism in amorphous materials is governed by their short-range order, which is strongly dependent on composition. In this talk, I discuss the effect of the composition on the magnetic properties and potential topological states in amorphous Fe_xGe_1-x films (x=0.4-0.6), grown by co-evaporation at cryogenic temperature. The film homogeneity is quantified by atomic force microscopy, energy dispersive X-ray spectroscopy and X-ray reflectometry. The field and temperature dependence of the saturation magnetization, magnetic anisotropy and magnetic domain formation are studied in terms of Kerr microscopy, vibrating sample magnetometry, ferromagnetic resonance spectroscopy, and magnetoresistance.