Title of Dissertation: NONLINEAR SPIN DYNAMICS AND ULTRA-FAST PRECESSIONAL SWITCHING

This thesis is intended to provide a theoretical analysis of magnetization dynamics in nanometer scale structures over picosecond time scales. This research has been motivated by promising technological applications in the area of magnetic data storage, as well as by pure scientific quest for ultra-fast spin dynamics in nanostructures. The present paradigm of magnetic data storage is approaching its fundamental limits for areal storage density, as well as for speed in data processing. As a result, there is an urgent need for reliable alternatives to current magnetic recording media, which are based on longitudinal thin film, and to the conventional mechanism of magnetization reversal, based on damping switching. In this dissertation, faster modes of magnetization reversals, using precessional magnetization motion, are analyzed in traditional longitudinal media and in its promising alternatives: perpendicular and patterned media. This analysis uses multi-spin description of magnetic nanoparticles and continuum micromagnetics for thin film media. The spins dynamics in both discrete and continuum versions is modeled by Landa