µMAG Standard Problem #4 results

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Solution directory


Submitted Solution: Gonçalo Albuquerque, Jaques Miltat and André Thiaville

Date:
July 18, 2000
From:
Gonçalo Albuquerque, Jaques Miltat and André Thiaville,
Laboratoire de Physique des Solides,
Bâtiment 510, Université de Paris-Sud, 91405 Orsay Cedex
Contact:
G. Albuquerque

These calculations used done using a finite difference scheme, with one cell across the thickness of the sample. Magnetostatic interactions were calculated using FFT techniques assuming constant volume charges within each cell and fields calculated at the center of each cell. Exchange interactions were calculated for the four neighbors of each cell, along each relevant axis. Boundary conditions were accurately enforced [M. Labrune and J. Miltat, J. Magn. Magn. Mater. 151, 231 (1995)]. Two meshings were used, approx. 2 nm cells and approx. 4 nm cells.

The time integration was done using a semi-implicit Crank-Nicholson scheme with accuracy feedback from monitoring of the damping coefficient, maximum torque and total energy.

For an approx. 4 nm mesh size, the results are insensitive to the time step in the range of 10-50 fs (femtoseconds). A time step of 25 fs was used to calculate the results shown below.

Results:

Raw data:

Time series data contain 4 columns: time (ns), M_x/M_s, M_y/M_s, M_z/M_s. Vector data is in 6 columns: x, y, z coordinates, and M_x/M_s, M_y/M_s, M_z/M_s vector components.

References:

G.Albuquerque, J.Miltat and A.Thiaville, IMACS 2000 World Congress Proceedings
G.Albuquerque, J.Miltat and A.Thiaville, Joint MMM-Intermag Conference 2001 (presentation)

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21-DEC-2005