Regensburg 2010 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 20: Micromagnetism / Computational Magnetics
MA 20.3: Vortrag
Mittwoch, 24. März 2010, 17:30–17:45, H22
Magnetic friction - from thin films to slabs — •Martin P. Magiera1, Dietrich E. Wolf1, and Ulrich Nowak2 — 1Faculty of Physics and CeNIDE, University of Duisburg-Essen, 47048 Duisburg, Germany — 2Department of Physics, University of Konstanz, 78457 Konstanz, Germany
Energy dissipation in magnetically interacting systems attract increasing interest recently (e.g. [1]). We study the magnetic contribution to friction force by atomistic computer simulations [2]: A substrate is modeled in the framework of the anisotropic Heisenberg model. Parallel to the substrate a dipole is moved with constant velocity, affecting the substrate spins by dipolar interaction. We integrate the stochastic Landau-Lifshitz-Gilbert equation for each substrate spin. Friction force can be calculated from the energy dissipation rate.
For T=0, friction can be understood by virtue of a macrospin model; it is “viscous” and proportional to the damping constant α [2]. Depending on substrate thickness, tip strength and scanning velocity, we observe a transition between two states, which directly changes the strength of magnetic friction by one order of magnitude. At T>0, the strict α-proportionality breaks down, and inverts above T0. For this regime we present an intriguing consistence of an algebraic temperature-decay of friction with the critical decay of the susceptibility above Tc.
[1] D. Kadau, A. Hucht and D.E. Wolf, PRL 101, 137205 (2008)
[2] M.P.Magiera, L. Brendel, D.E. Wolf and U. Nowak, EPL 87, 26002 (2009)