Magnetic Nanowires for RF Applications: Ferromagnetic Resonance and Permeability Characterization

Magnetic nanowires show promising potential in non-reciprocal device design and emerging areas like cells labeling in nano-medicine applications. One challenge, however, is how to obtain ferromagnetic resonance frequency (FMR) and complex permeability in a simplistic manner. In this study, a through line and short-circuited CPW circuits were used to obtain FMR in DC magnetic field and frequency domains, respectively. Factors were investigated to understand how magnetic field absorption is affected by sample placement on the circuit, how FMR is impacted by the angle between wire axis and DC field, and how complex permeability can be extracted from the reflection data. Using the “four steps” method which was commonly used for thin films [1–3], we obtain FMR of 27 GHz at 0.4T and complex permeability values of µ’=7 and µ”=4.5, respectively for cobalt nanowires (pH=2).