Magnetic imaging of skyrmions in a thin film

Magnetic skyrmions are topologically protected, nanoscale, whorls and hedgehogs of magnetization. Because of their topological properties skyrmions also give rise to novel phenomena such as the topological Hall effect. Low temperature magnetic force microscopy (MFM) provides us with a tool for both imaging and control of skyrmions. Here I will describe recent experiments on multilayer Ir/Fe/Co/Pt stacks which can host Néel (hedgehog) skyrmions. We use MFM to image the magnetic structure in the films as a function of temperature and magnetic field. This allows us to explore the correspondence between the topological Hall effect and the magnetic textures that we image. For the analysis we rely on a new simple model for the magnetic field from a skyrmion.