Ferromagnetic resonance measurements of Fe nanodots epitaxially grown on a MgO layer were carried out using a coplanar waveguide to investigate the dynamic behaviours of spins in a magnetic dot assembly. The resonant peaks of Fe nanodots with an average diameter of 10 nm were successfully observed, and a strong magnetic anisotropy was found in the peak frequency shift depending on the magnetic field applied in the film plane. A difference was clearly seen in the peak shift behaviour between Fe nanodots and continuous Fe thin films. The Gilbert damping parameter of the Fe nanodots (nominal thickness: 3 nm) was estimated to be 0.008 12 from the width of the resonant peaks, substantially larger than that of a continuous Fe thin film with a thickness of 8 nm. This difference in damping is attributed to the distribution of the effective field in each nanodot due to size dispersion. Ferromagnetic resonance studies using coplanar waveguides thus enable clarification of the spin dynamics of magnetic dot arrays and the fundamental spin dynamics of a single nanodot.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Acoustics and Ultrasonics
- Surfaces, Coatings and Films