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 20.75: Poster
Dienstag, 27. März 2012, 12:15–15:15, Poster A
Ultrafast Demagnetization Dynamics in Ni1−xPdx alloys — •Moritz Plötzing1, Patrik Grychtol1, Roman Adam1, Claus M. Schneider1, Hans Nembach2, Justin Shaw2, Tom Silva2, Oliver Schmitt3, Daniel Steil3, Mirko Cinchetti3, and Martin Aeschlimann3 — 1Peter Grünberg Institut, PGI-6, Research Center Jülich, 52425, Jülich, Germany — 2Electromagnetics Division, National Institute of Standards and Technology, Boulder, Colorado 80305-3328, USA — 3University of Kaiserslautern and Research Center OPTIMAS, 67663, Kaiserslautern, Germany
In the presented work, we investigated alloys of Ni and Pd with varying mixing ratios focusing on the magnetization dynamics on different timescales. For this purpose, we characterized the samples using a vibrating sample magnetometer and ferromagnetic resonance in order to determine the Curie temperature TC and the picosecond dynamics, respectively. The latter is described by the Gilbert damping parameter α. Both quantities depend strongly on the stoichiometry and can be tuned very precisely over a wide range by changing the Pd concentration. Additionally, we carried out a thorough investigation of the laser-induced demagnetization time τM on the femtosecond timescale employing a time-resolved MOKE setup. According to the theoretical model published in [1], the dynamics on both timescales is related and the proportionality is mainly defined by TC. Using the measured values for α and τM, we study the applicability of the theory for a ferromagnetic d-alloy and consequently the underlying fundamental processes.
[1] Koopmans et al., Phys. Rev. Lett. 95, 267207 (2005)