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