Magnetic whirls with a diameter of only a few nanometers occur in a thin film of palladium and iron (bottom, cones represent single atoms of the surface and they point into the direction of the atomic magnets). The resistance, measured with a metallic probe close to the surface changes inside the skyrmion as compared to its surrounding (top, experimental data across a skyrmion, see original publication). The change in resistance is continuous and becomes strongest, when the canting between neighboring atomic magnets is largest, in this case in the skyrmion center. (Image: C. Hanneken, University of Hamburg)

For more details refer to the following links:

C. Hanneken et al., Nat. Nanotech. 10, 1039 (2015)

M. Perini et al., Phys. Rev. Lett. 123, 237205 (2019)

Press release of the CAU (2015): Simple detection of magnetic skyrmions