2024/06/26 by Sanjay Ashok, Jonas Hoefer, Ashok, Sanjay +11 · 1 citation
Engineering · Physics and Astronomy · #Characterization and Applications of Magnetic Nanoparticles #FOS: Physical sciences #Magnetic properties of thin films #Materials Science (cond-mat.mtrl-sci) #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Theoretical and Computational Physics
paper · pdf · doi:10.48550/arxiv.2406.18686
openalex publication_date 2024/06/26 · openalex created_date 2024/06/29 · openalex updated_date 2026/08/01
We calculate the influence of diffusive and ballistic transport on ultrafast magnetization in thick metallic films. When only diffusive transport is present, gradients of magnetization in the material remain up to picosecond timescales. In contrast, in the extreme superdiffusive limit where ballistic transport dominates, the magnetization changes homogeneously in space. We calculate the measurable magneto-optical responses for a \SI40\nano\meter Nickel film. Although the resulting Kerr rotation dynamics are found to be very similar in the two limits of transport, our simulations reveal a clear signature of magnetization gradients in the Kerr ellipticity dynamics, namely a strong probe-angle dependence for the case when diffusive transport allows gradients to persist. We then perform probe-angle dependent complex magneto-optical Kerr effect (CMOKE) measurements on an excited \SI40\nano\meter Nickel film. The angle dependence of the measured Kerr signals closely matches the simulated response with diffusive transport. Therefore we conclude that the influence of ballistic transport on ultrafast magnetization dynamics in such films is negligible.