Detection of magnetic skyrmion tubes in cubic B20 FeGe nanostructures

In chiral helimagnets with the non-centrosymmetric cubic B20 crystal structure, such as FeGe, host magnetic Bloch-type skyrmions due to the Dzyaloshinskii-Moriya interaction (DMI). Although magnetic skyrmions are depicted as two-dimensional spin textures in bulk crystals, in reality, they possess a three-dimensional structure of skyrmions that looks like elongated tubes extending throughout the thickness of the sample. We have synthesized single-crystal FeGe nanowires (NWs) and Fe_1-xCo_xGe (x<0.1) nanoplates (NPLs) via chemical vapor deposition (CVD) to explore these magnetic skyrmion tubes (SkT) in geometrically confined nanostructures. Lorentz transmission electron microscopy imaging as well as magnetotransport measurements confirmed that skyrmions are stabilized in a wider magnetic field (B_ext) and temperature region in these nanostructures in comparison to the bulk materials. Furthermore, magnetoresistance measurements on FeGe nanostructures have shown some unusual features when B_ext is parallel to the current direction. In conjunction with magnetic contrast imaging techniques and micromagnetic simulations, we have further explored the spin modulation of SkT with the variation of in-plane applied magnetic field in FeGe nanostructures.