Dynamics of coupled vortices in a pair of ferromagnetic disks

We here experimentally demonstrate that coupled gyration modes can be resonantly excited primarily by the ac current in a pair of ferromagnetic disks with varied separating distance. The sole gyrotropic mode clearly splits into a higher and a lower frequency modes for different configurations of polarities via dipolar interaction. These experimental results indicate that the magnetostatically coupled pair of vortices behaves similar to a diatomic molecule with bonding and anti-bonding states. These findings lead to the possible extension of designing the magnonic band structure in a chain or an array of vortices.Comment: 4 pages, 4 figures, accepte

All-Optical Excitation and Detection of Picosecond Dynamics of Ordered Arrays of Nanomagnets with Varying Areal Density

We have demonstrated optical excitation and detection of collective precessional dynamics in arrays of coupled Ni80Fe20 (permalloy) nanoelements with systematically varying areal density by an all-optical time-resolved Kerr microscope. We have applied this technique to precisely determine three different collective regimes in these arrays. At very high areal density, a single uniform collective mode is observed where the edge modes of the constituent elements are suppressed. At intermediate areal densities, three nonuniform collective modes appear and at very low areal density, we observe noncollective dynamics and only the centre and edge modes of the constituent elements appear.Comment: 12 pages, 4 figure