Regensburg 2004 – wissenschaftliches Programm

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MA: Magnetismus

MA 13: Poster:Schichten(1-23),Spinabh.Trsp(24-41),Exch.Bias(42-56),Spindyn.(57-67),Mikromag.(68-76),Partikel(77-90),Spinelektr.(91-97),Elektr.Theo.(98-99),Mikromag+PhasÜ+Aniso.(100-105),Magn.Mat.(106-118),Messmethod.(119-121),Obflm.+Abbverf.(122-123)

MA 13.75: Poster

Dienstag, 9. März 2004, 15:00–19:00, Bereich A

Magnetic relaxation and ordering in nanostructured thin films during growth: A cluster Monte Carlo study — •Roman Brinzanik, Peter J. Jensen, and Karl Heinz Bennemann — Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany

We calculate the nonequilibrium and equilibrium remanent magnetization of inhomogeneous island-type thin films. The transition from dipole-coupled islands at low coverages to a strongly connected ferromagnetic film at high coverages during film growth is analysed [1]. The single-island magnetic anisotropy and inter-island dipole and exchange couplings are taken into account. A cluster Monte Carlo method is developed which includes coherent magnetization rotations of connected islands. This method enables calculations of the magnetic properties in the whole coverage range within the same model [2].

For coverages below the percolation threshold, we obtain collectively ordered magnetic states due to the dipole interaction with ordering temperatures of 1 – 10 K for the assumed model parameters. The anisotropy causes pronounced nonequilibrium effects with blocking temperatures of the order 10 – 100 K. The dipole interaction somewhat increases the blocking temperatures.

[1] U. Bovensiepen, P. Poulopoulos, W. Platow, M. Farle, K. Baberschke, J. Magn. Magn. Mater. 192, L386 (1999)

[2] R. Brinzanik, P. J. Jensen, K. H. Bennemann, Phys. Rev. B 68, 174414 (2003)