Domain wall displacement in Py square ring for single nanometric magnetic bead detection

An approach based on domain wall displacement in confined ferromagnetic nanostructures for attracting and sensing a single nanometric magnetic particle is presented. We modeled and experimentally demonstrated the viability of the approach using an anisotropic magnetoresistance device made by a micron-sized square ring of Permalloy. This detection concept can be suitable to biomolecular recognition and, in particular, to single molecule detection.