Detection of ferromagnetic particles using spin valve sensors

Abstract

We have attached single ferromagnetic particles of 8 μm diameter to the tips of microfabricated atomic force microscope cantilevers. These cantilevers were magnetized to fix the magnetization direction of the ferromagnetic particles and scanned in a controlled manner over a spin valve structure of dimension 12 × 8 μm2. Two dimensional image scans representing the change in resistance of the spin valve due to a scanning bead were obtained. The results are explained using a simple model where the scanning bead is treated as a pure dipole. © 2006 American Institute of Physics.