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 evolution of spatially averaged magnetization components, 2.5 nm
cells.
The magnetization distribution corresponding to the first time
< Mx > = 0, with 2.5 nm cells.
Color indicates my-component.
Effects of cell size on time evolution of
< my >.
Time evolution of spatially averaged magnetization components, 2.5 nm cells.
The magnetization distribution corresponding to the first time
< Mx > = 0, with 2.5 nm cells.
Color indicates my-component.
Effects of cell size on time evolution of
< my >.
Vector data has 5 columns: x, y position in cells (each cell is 2.5 nm), and mx, my, mz normalized vector components.