µMAG Standard Problem #4 results

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Submitted Solution: Pierre E. Roy and Peter Svedlindh

November 18, 2005.
Pierre E. Roy and Peter Svedlindh
Department of Engineering Sciences, Ångström Laboratory, Box 534, SE-751 21 Uppsala University, Uppsala, Sweden
Pierre E. Roy

For these calculations, a finite difference scheme has been used with 3D spins on a 2D mesh (since the thickness of the particle is well below the exchange length). Exchange interactions were calculated for 4 nearest neighbors using the 5-point approximation for the Laplacian. Demagnetizing fields have been computed with FFT methods (W.H. Press, B.P. Flannery, S.A. Teukolsky, William T. Vetterling, Numerical Recipes, The Art of Scientific Computing, Cambridge University Press 1988) and the analytical expressions for the evaluation of the demagnetization tensor used were taken from Newell et al. (A. J. Newell, W. Williams, and D. J. Dunlop, J. Geophys. Res. 98, 9551 (1993)). For the integration of the Landau-Lifshitz equation of motion, a 4th order Runge-Kutta scheme was implemented. Two discretization cell sizes have been considered: 5nm and 2.5nm.



Time series data contain 4 columns: time (ns), mx, my, mz. These files are gzipped compressed; uncompressed the data files are each roughly 68 MB for the 2.5 nm mesh data and 16 MB for the 5.0 nm mesh data.

Vector data has 5 columns: x, y position in cells (each cell is 2.5 nm), and mx, my, mz normalized vector components.

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