Regensburg 2013 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 50: Poster II

MA 50.56: Poster

Freitag, 15. März 2013, 10:30–13:30, Poster D

Collective Switching of Nanoparticles in Magnetic Arrays — •David Altwein, Elena Vedmedenko, Robert Wieser, and Roland Wiesendanger — Institute of Applied Physics, University of Hamburg, Jungiusstr. 11, 20355 Hamburg, Germany

Numerical simulations of the switching of ensembles of superparamagnetic nanoparticles in the framework of the Langevin Spin Dynamics as well as the path integral formalism are reported and compared with experimental results. The particles have been coupled via dipolar or RKKY interactions. In the case of a strong coupling a collective switching of particles has been observed. The continuous decrease of the coupling’s strength leads to a continuous decrease in the coherency of the switching. The phase shift of the switching as a function of the interaction strength shows a gradual change similar to that of the order parameter in the second order phase transition. This dynamical phase transition is discussed and compared with existing theoretical models.