  Topologically non-trivial spin textures, such as skyrmions and dislocations,
display emergent electrodynamics and can be moved by spin currents over
macroscopic distances. These unique properties and their nanoscale size make
them excellent candidates for the development of next-generation logic gates,
race-track memory, and artificial synapses for neuromorphic computing. A major
challenge for these applications - and the investigation of nanoscale magnetic
structures in general - is the realization of adequate detection schemes that
provide the required resolution and sensitivity. Here, the local magnetic
properties of topological defects in FeGe are studied, revealing a pronounced
non-linear response that distinguishes the individual spin textures from the
helimagnetic background. Combining magnetic force microscopy and micromagnetic
simulations, the non-linear response is linked to the local magnetic
susceptibility, representing an innovative approach for detecting topologically
non-trivial spin textures and domain walls. Based on the findings, a read-out
scheme is proposed using planar micro-coils compatible with semiconductor
fabrication methods, facilitating the transfer to spintronics devices.
