Magnetic Nanowire Biolabels Using Ferromagnetic Resonance Identification

Nanomaterials have attracted attention from a variety of fields. For example, magnetic nanowires (MNWs) can be used to identify and/or distinguish objects using their magnetic signatures: first-order reversal curves, hysteresis curves, angle-dependent coercivity, and ferromagnetic resonance (FMR). Among these, FMR is the fastest measurement, and it shows the potential to identify many high-frequency signatures simultaneously. In this work, iron, cobalt, and nickel MNW samples are fabricated by template-assisted pulsed electrodeposition and are measured individually and in combination using an FMR-identification (FMR-ID) labeling system. The FMR-ID system is then optimized using the FMR measurement results, the original and revised Kittel equations, and the magnetic properties of the MNWs. The most efficient FMR-ID systems will use DC bias fields (0–15 kOe) that are parallel to the nanowires and microwave frequencies of 20 GHz or above. These MNW-based FMR-ID labeling systems will be effective wherever small identification markers are needed.