µMAG Standard Problem #4 results

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Solution directory

• Comparisons
• G. Albuquerque, J. Miltat and A. Thiaville
• R. D. McMichael, M. J. Donahue, D. G. Porter, and J. Eicke
• Liliana Buda, Lucian Prejbeanu, Ursula Ebels and Kamel Ounadjela
• E. Martinez, L. Torres and L. Lopez-Diaz
• José L. Martins and Tania Rocha
• P.E. Roy and P. Svedlindh
• Massimiliano d’Aquino, Claudio Serpico, and Giovanni Miano
• Dmitri Berkov
• M. J. Donahue and D. G. Porter
• Rasmus Bjørk, E. B. Poulsen and A. R. Insinga

Submitted Solution: M. J. Donahue and D. G. Porter

Date:

September 25, 2014.

From:

M. J. Donahue and D. G. Porter
National Institute of Standards and Technology, Gaithersburg, MD 20899

Contact:

Michael Donahue

An earlier contributed solution came from the original 2D mmSolve2D program in OOMMF. This new submission comes from the OOMMF eXtensible solver. The mesh is a 3D array of 1 nm cubes. The exchange energy was calculated using a "six-neighbor dot product" representation. The maximum time step was set at 0.2 ps, but smaller time steps are taken when necessary to keep the error within certain bounds. All other simulation components were used in their default configuration. Data from the simulation was captured and archived at every 1 ps of simulation time.

Results:

• For the first part of the problem, with the field applied 170° from the x-axis (Field 1), the maximum angle between neighboring spins on the lattice was about 6° at about 300 ps.

  
  a plot of the spatially averaged magnetization

  
  and an image of the magnetization when M_x first crosses zero. The background color indicates the z component of magnetization, with blue directed away from the viewer and red directed toward the viewer.

• For the second part of the problem, with the field applied 190° from the x-axis (Field 2), the maximum angle between neighboring spins on the lattice was about 18° at about 580 ns.

  
  A plot of the spatially averaged magnetization

  
  and an image of the magnetization when M_x first crosses zero. The background color indicates the z component of magnetization, with blue directed away from the viewer and red directed toward the viewer.

Raw data:

• Field 1: Time series and Vector data at M_x=0.
• Field 2: Time series and Vector data at M_x=0.

Supplemental material:

• MIF files: Create initial state, Part 1, Part 2.
• Initial state
• Plot generation: gnuplot script
• Magnetization image generation: avf2ppm configuration