MAGNETO-OPTICAL MEASUREMENTS OF COLLECTIVE SPIN DYNAMICS OF TWO-DIMENSIONAL ARRAYS OF FERROMAGNETIC NANOELEMENTS

Abstract

Magnetic nanodot arrays are interesting systems for future applications in nanotechnology including patterned magnetic media, magnonic crystals, magnetic logic, sensors, STNOs and biomedical applications. All applications require the knowledge base of magnetization processes of magnetic nanodot arrays at various time and length scales. Here, we review the present status of experimental studies of picosecond precessional magnetization dynamics in magnetic nanodot arrays. We discuss the fabrication methods of magnetic nanodot arrays and excitation and detection methods of precessional dynamics by optical means. We further discuss the all-optical excitation and detection of precessional dynamics in Ni80Fe20 (permalloy) nanodot arrays with width between 200 nm and 50 nm and with interdot separation between 50 nm and 400 nm. A transition from strongly collective dynamics to completely isolated dynamics through various weakly collective regimes, variation of precession frequency and damping with the interdot separation, effects of dipolar and quadrupolar interdot interaction, effects of the variation of dot size on the dynamics of single elements and arrays, and anisotropy of collective dynamics have been thoroughly studied by experimental and micromagnetic simulation results. Finally, we discuss the future directions in the research on the dynamics of magnetic nanodot arrays.