Helical and skyrmion phases in amorphous Fe-Ge thick films*

Magnetic skyrmions are topologically protected solitons with the potential to revolutionize future spintronics and computing due to its low energy cost of manipulation. Skyrmion phase, now found in various single crystals including ferrimagnet FeGe, has recently predicted to also manifest in vector spin frustrated amorphous films. We studied amorphous Fe-Ge films using coherent resonant soft x-ray scattering. We observed magnetic Bragg peaks associated with the helical and skyrmion periodicity and mapped out their field-temperature phase diagram. We also observed spontaneous dynamics for a large range of temperatures. We calculate the respective one-time correlation functions of this fluctuation, whose characteristic curvatures indicate the distinct dynamical behavior of the helical and skyrmion textures.