The working group “Nano Magnonics” investigates dynamic processes in ferromagnetic thin-film systems. Structures with layer thicknesses in the range of 5 to 50 nanometers are studied. Lateral dimensions range from 50 nanometers up to few micrometers, covering the length scales of patterned magnetic storage elements. Soft magnetic materials, like iron, cobalt and nickel, as well as their alloys, exhibit fundamental magnetic lengths (so-called exchange lengths) on this length scale. Switching times of current magnetic applications approach the sub-nanosecond regime. This intrinsic time scale of the magnetization dynamics is defined by the gyroscopic precession of individual magnetic moments.
Both, the static equilibrium configuration and the dynamic behavior of magnetic microstructures depend essentially on their shape and size. In response to the excitation with fast varying magnetic fields, fundamental magneto-dynamic phenomena appear, like fast movement of magnetic domain walls, the dynamics of the magnetic vortices as well as fast switching of the magnetization. In the case of magnetic multilayers, the dynamical coupling of different magnetic layers is observed. Furthermore, magnetic relaxation processes after the excitation are of great interest. Fundamental questions currently being intensively investigated are, for example, the source and the role of damping in magnetization dynamics.
Spatial extent of the smallest micromagnetic configurations, i.e. the magnetic domain walls and the magnetic vortex-cores, is determined by the characteristic exchange length of the material. The exchange length of technologically highly important soft magnetic nickel-iron-alloy (Ni 80%, Fe 20%, Permalloy) amounts to less than 6 nanometers. Analytical tools with high temporal and spatial resolution are necessary in order to investigate the static and the dynamic behavior of such structures in detail. We are using time-resolved magnetic transmission x-ray microscopy for the visualization of magnetization dynamics in small magnetic structures.
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Magnetism in Antidot LatticesHole patterns in magnetic materials, so called antidot lattices, on the nano scale exhibit a large number of novel phenomena. |
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Dynamic of Magnonic CrystalsArtificial crystals for magnons or spin waves are imaged by high resolution time resolved x-ray microscopy. |
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Micromagnetic simulationsIn addition to the experiments, micromagnetic simulations of the spin dynamics are also being performed by our working group. |
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First-Order Reversal CurvesFast high resolution first-order reversal curve measurements yield a unique insight into magnetization reversal processes. |
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Camu is our mascot that follows our daily lives as scientists and makes Instagram posts about his adventures. He is trying to reach out to students, pupils, and the general public to show how interesting nanomagnonics can be. Follow him on Instagram! @camudasnanomagnomel |
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