Imaging skyrmions in B20 epitaxial thin films grown on Si substrates using variable temperature Magnetic Force Microscopy (MFM)

In the search for the next-generation magnetic storage, tuning the size of the skyrmions with high Curie temperatures (T_c) promotes the possibility to use them for such application. We have successfully grown Fe-rich Fe_1.2Ge thin films using Molecular Beam Epitaxy (MBE) with a T_c higher than the room temperature. Furthermore, we have observed skyrmions in the Fe-rich Fe_1.2Ge thin films at room temperature. Here, we report the first time imaging of the skyrmions in FeGe and Fe rich Fe_1.2Ge epitaxial thin films grown on Si substrates using Magnetic Force Microscopy (MFM). Based on the MFM images, skyrmions were observed in temperatures and magnetic fields consistent with the topological Hall measurements for the FeGe thin films. Additionally, the topological Hall resistance scales down with the density of skyrmions at lower temperatures in these films. Also, we observed skyrmion motion and annihilation which might be driven by the stray field of the MFM tip probably due to the defects in the FeGe films.