Characterization of Magnetization Dynamics in Structured Magnetic Films
The focus of this thesis is investigating of the magnetization dynamics in patterned magnetic films by time-resolved Kerr microscopy (TR-MOKE). Therefore, various magnetic films and structures are studied using the developed TR-MOKE and inductive microwave magnetometry setup. The results of this thesis reveal new aspects of complicated magnetization dynamics in such magnetic systems. Also, it provides the knowledge of tailoring dynamic magnetic properties of modern magnetic structures. Initially, the magneto-dynamic response of Landau-like magnetic domain configurations are examined and a method to separate the in- and out-of-plane Kerr signals is proposed. This method indicates a more elaborated model for fast magnetization processes in soft magnetic elements. In addition, the direct observation of spin-wave generation and propagation from oscillating pinned magnetic structures is reported, and the fundamental properties of them are analyzed. Using this knowledge, an alternative way to generate and propagate spin waves that do not require any artificial structure (e.g., antenna or wave-guide) is proposed. Moreover, the results of experimental TR-MOKE imaging together with complementary micromagnetic simulations were used to design an experiment, where the spin waves are emitting from magnetic elements corners and edges. The frequencies of such spin waves shown to be tunable by the excitation frequency. Finally, the dynamic magnetic response of weak antiferromagnetically coupled and structured magnetic films are presented. The multilayer film dynamic properties are compared to the single-layer film, and the impact of patterning on magnetization dynamics is shown.
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