Study of microwave-assisted magnetization dynamics in magnetic films and structures

Abstract

Microwave-assisted magnetization reversal (MAMR) has been suggested as an alternative recording scheme to extend areal densities in hard disk drives beyond 1 Tb/in². In this thesis, microwave-assisted magnetization dynamics have been characterized in different spatial regimes by electrical and optical techniques to understand their influence on reversal processes. Time-resolved optical techniques have been developed to study spin wave generation in large area patterned thin films and the interaction of different modes. The study revealed the influence of pattern geometry on the spin wave modes and their interference patterns at different distances. Additionally, MAMR has also been investigated in individual elements by X-ray microscopy techniques to temporally and spatially map the spin wave contribution to the reversal mechanism. The study showed that spin waves are the dominant driving mechanism of reversal in small elements. Finally, a novel electrical characterization technique for MAMR using the spin-pumping phenomenon is demonstrated.