Mapping the magnetic field of skyrmions and spin spirals by scanning probe microscopy

Abstract This chapter reviews scanning probe microscopy methods that measure the field above a sample contain chiral spin textures. Among those microscopy methods are magnetic force microscopy (MFM), nitrogen vacancy (NV) center microscopy, scanning Hall probe microscopy, and scanning SQUID microscopy. However, only the first two techniques have been applied for the study of chiral spin textures. They can obtain a lateral resolution down to about 10 nm and are sufficiently sensitive to map the stray field from ferromagnetic layer with a thicknesses down to a few atoms. Even submonolayer of spins can be imaged. The information on the magnetic moment distribution inside the sample that can be obtained from the stray field however remains limited because different magnetic moment configurations can generate the same stray field. Thus in most cases the field of candidate magnetization structures is fitted to experimental results. An important advantage of methods imaging the stray field is that these can be applied to sample where the magnetic layer is inside the sample, i.e., below a layer protecting it against oxidation. This makes these experimental methods suitable for the reliable imaging of technologically relevant samples.