FMR Detection of Magnetic Nanowires (MNW) for Tagging and Sensing Applications

Magnetic Nanowires (MNWs) are magnetic particles with high shape anisotropies. The high anisotropy of the nanoparticle enhances the coercivity and remnant magnetization compared to other nanoparticles of the same material. This effect makes MNWs desirable for use in applications where resistance to external magnetic fields or square hysteresis loops are advantageous at smalls size scales. FMR (Ferromagnetic Resonance) is one such application, where the orientation of the particle or film magnetization with respect to an external magnetic field is critical in the prediction of the resonance frequency. Here, FMR of MNWs are used to detect MNWs with a specific signature. This signature is dictated by the concentration, material, and orientation of MNWs in a DC Magnetic Field. Detection occurs by setting a specific applied AC Frequency, along with the position and magnitude of an applied DC magnetic field. In this work, such detection is performed for MNWs of ferromagnetic materials and their alloys. Potential applications for such a device include bio-applications such as the detection of compound concentration and selectively heating tagged organisms in a cryobank. However, applications could reach as far as broader sensing applications and advanced security.