2. Guided Tour

We present a number of worked out examples that are explained in detail and should cover most of the usual applications. (You may also want to check the Frequently Asked Questions.)

• 2.1. Example: Demag field in uniformly magnetised sphere
  • 2.1.1. Importing nmag
  • 2.1.2. Creating the simulation object
  • 2.1.3. Defining (magnetic) materials
  • 2.1.4. Loading the mesh
  • 2.1.5. Setting the initial magnetisation
  • 2.1.6. Setting the external field
  • 2.1.7. Extracting and saving data
    • 2.1.7.1. Saving averaged data
    • 2.1.7.2. Extracting arbitrary data from the running program
    • 2.1.7.3. Saving spatially resolved data
• 2.2. Example 2: Computing the time development of a system
  • 2.2.1. Mesh generation
  • 2.2.2. The simulation
  • 2.2.3. Analysing the data
    • 2.2.3.1. Time dependent averages
    • 2.2.3.2. Comparison with OOMMF and Magpar
    • 2.2.3.3. Spatially resolved fields
  • 2.2.4. Higher level functions
  • 2.2.5. “Relaxing” the system
  • 2.2.6. “Relaxing” the system faster
  • 2.2.7. Decreasing execution time
• 2.3. Example: Simple hysteresis loop
  • 2.3.1. Hysteresis simulation script
  • 2.3.2. Hysteresis loop computation
  • 2.3.3. Obtaining the hysteresis loop data
  • 2.3.4. Plotting the hysteresis loop with Gnuplot
• 2.4. Example: Hysteresis loop for Stoner-Wohlfarth particle
  • 2.4.1. Plotting the hysteresis loop
• 2.5. Example: Hysteresis loop for thin disk
  • 2.5.1. Thin disk hysteresis loop
• 2.6. Example: Vortex formation and propagation in disk
• 2.7. Example: Manipulating magnetisation
  • 2.7.1. Modifying the magnetisation
• 2.8. Example: IPython
• 2.9. Example: Pinning Magnetisation
  • 2.9.1. Pinning simulation script
  • 2.9.2. Pinning magnetisation
  • 2.9.3. Visualisation
• 2.10. Example: Uniaxial anisotropy
  • 2.10.1. Uniaxial anisotropy simulation script
  • 2.10.2. Visualization
  • 2.10.3. Comparison
• 2.11. Example: Cubic Anisotropy
  • 2.11.1. Cubic anisotropy simulation script
  • 2.11.2. Analyzing the result
• 2.12. Example: Arbitrary Anisotropy
  • 2.12.1. Arbitrary anisotropy simulation script
  • 2.12.2. The result
• 2.13. Restart example
  • 2.13.1. Saving the state of the simulation
  • 2.13.2. Starting and restarting the simulation
• 2.14. Applying a field that changes both in time and in space
  • 2.14.1. Idea: pass simulation object to field-setting function
  • 2.14.2. Complete example: simple moving write-head example
• 2.15. Example: two different magnetic materials
• 2.16. Example: Larmor precession
• 2.17. Example: 1D periodicity
  • 2.17.1. Introduction periodic boundary conditions (“macro geometry”)
  • 2.17.2. 1d example
• 2.18. Example: 2D periodicity
• 2.19. Example: Spin-waves in periodic system
  • 2.19.1. Relaxation script
  • 2.19.2. Visualising the magnetisation evolution
• 2.20. Example: post processing of saved field data
• 2.21. Example: Spin transfer torque (Zhang-Li model)
  • 2.21.1. Current-driven motion of a vortex in a thin film
  • 2.21.2. Part I: Relaxation
  • 2.21.3. Part II: Current driven dynamics
  • 2.21.4. Standard problem
• 2.22. Example: Current-driven magnetisation precession in nanopillars
  • 2.22.1. Two simulations in one single script
  • 2.22.2. Results: precession of the magnetisation
• 2.23. Mesh distortion for edge roughness simulation
  • 2.23.1. Example
  • 2.23.2. Details and command line options
• 2.24. Compression of the Boundary Element Matrix using HLib
  • 2.24.1. Hierarchical Matrices in Micromagnetism
  • 2.24.2. Installation of HLib
  • 2.24.3. Testing the HLib BEM Matrix compression
  • 2.24.4. Using HLib example 1: Demagnetisation Field of a Sphere
    • 2.24.4.1. Using HLib with default parameters
    • 2.24.4.2. HLib Memory usage
    • 2.24.4.3. Changing the Parameters of HLib
  • 2.24.5. Using HLib Example 2: Thin Films
  • 2.24.6. HLib and MPI
• 2.25. Example: Calculation of dispersion curves
  • 2.25.1. The system: thesystem.py
  • 2.25.2. Part I: relaxation.py
  • 2.25.3. Part II: dynamics.py
  • 2.25.4. Postprocessing the data
• 2.26. Example: Timestepper tolerances
  • 2.26.1. Hysteris loop calculation not converging? A word of warning ...
• 2.27. Example: Parallel execution (MPI)
  • 2.27.1. Using mpich2
    • 2.27.1.1. Testing that nsim executes in parallel
  • 2.27.2. Using mpich1
  • 2.27.3. Visualising the partition of the mesh
  • 2.27.4. Performance
• 2.28. Restarting MPI runs
• 2.29. More than one magnetic material, exchange coupled