Berlin 2012 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 20: Poster I - Biomagnetism, FePt Nanoparticles, Magnetic Particles/Clusters, Magnetic Materials, Magnetic Semiconductors, Half-metals/Oxides, Multiferroics, Topological Insulators, Spin structures/Phase transitions, Electron theory/Computational micromagnetics, Magnetic coupling phenomena/Exchange bias, Spin-dependent transport, Spin injection/spin currents, Magnetization/Demagnetization dynamics, Magnetic measurement techniques

MA 20.74: Poster

Dienstag, 27. März 2012, 12:15–15:15, Poster A

Magnetization dynamics in Ni on the picosecond timescale — •Martin Lüttich¹, Jakob Walowski¹, Andreas Mann¹, Markus Münzenberg¹, Unai Atxitia², and Oksana Chubykalo-Fesenko² — ¹I. Physikalisches Institut, Universität Göttingen — ²Instituto de Ciencia de Materiales de Madrid

Magnetization dynamics of polycrystalline nickel films are measured using the all-optical pump-probe technique for various pump pulse fluences. The parallel treatment of photons, electrons, phonons and magnetic correlations of the system amounts a challenge to the microscopic theoretical description. At the same time different length and time scales are involved.

We investigate the influence of hot electrons on the relative demagnetization. Performing the experiment for different pump fluences, we measure a higher relative demagnetization at higher fluences. These results are compared to simulations with the Landau-Lifshitz-Bloch equation, which is based on a thermal model, and featured by the consideration of two electron temperature dependent relaxation times τ_⊥ and τ_||. The electron temperature needed as input for the simulations is extracted from experiments.