Anisotropic magnetoresistance in epitaxial FeGe thin films

The advent of skyrmion imaging and electrical detection is an exciting avenue of research as skyrmions hold promise for next-generation magnetic storage. Presently, in B20 materials, electrical measurements have focused on the detection of non-trivial topological spin textures via topological Hall effect. To further our understanding of transport properties in non-centrosymmetric materials that host skyrmions, we have performed angular-dependent magnetoresistance (ADMR) in the saturated magnetic phase. We have grown epitaxial B20 FeGe/Si(111) films by molecular beam epitaxy. Several features appear in the vicinity of the Curie temperature of 280 K that also persist well above this temperature. Additionally, these features are highly magnetic field dependent. At low temperatures, the signal is dominated by the anisotropic magnetoresistance (AMR) contribution. However, as we approach the magnetic ordering temperature, a strong six-fold symmetric contribution appears. This term, reflecting the crystal symmetry, possibly originates from the magneto-crystalline anisotropy. Curiously, this feature continues to grow in magnitude up to 14 T. We discuss possible origins of these effects above and below the Curie temperature.