Make Disk in OOMMF: Troubleshooting Uniaxial Anisotropy

  • Thread starter Ark236
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In summary, to see the evolution of the magnetization of a dot with uniaxial anisotropy, you will need to properly specify the magnetization and make sure the value of Ms is accurate.
  • #1
Ark236
22
3
Hi,
I'm just starting to use oommf. I wish to see the evolution of the magnetization of a dot, which has uniaxial anisotropy. Command lines I use are

#Geometry
proc Disco {x y z} {
global Diametro Ms
set rx [expr {2*$x-1}]
set ry [expr {2*$y-1}]

if {$rx*$rx+$ry*$ry>$Diametro*$Diametro/4.} {
return 0
}
return $Ms
}

#Atlas
Specify Oxs_BoxAtlas:atlas [subst {
xrange {0 $Diametro}
yrange {0 $Diametro}
zrange {0 $Altura}
}]

#Mesh

Specify Oxs_RectangularMesh:mesh [subst {
cellsize {$cellsize $cellsize $cell2}
atlas :atlas
}]

Specify Oxs_UniaxialAnisotropy {
axis { 0 0 1 }
K1 2e5
}Specify Oxs_UniformExchange [subst {
A 1.6e-11
}]

Specify Oxs_CGEvolve:evolve {}

Specify Oxs_MinDriver [subst {
evolver Oxs_CGEvolve
stopping_mxHxm 0.1
mesh :mesh
Ms { Oxs_ScriptScalarField {
atlas :atlas
script {Disco 2.2e5}
}}
m0 { Oxs_RandomVectorField {
min_norm 1.0
max_norm 1.0
}}
}]

but when the data stored mmarchive through, the file contains only zeros. Why?

Thanks
 
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  • #2
in advance.It is possible that you have not correctly specified the magnetization of your system. The command line for specifying the magnetization should look like this: Specify Oxs_ScriptScalarField { atlas :atlas script {Disco 2.2e5}}Additionally, make sure that the value of Ms that you are using (2.2e5) is realistic for the material that you are simulating.
 

1. What is "Make Disk" in OOMMF?

"Make Disk" is a command in OOMMF (Object Oriented Micromagnetic Framework) that allows users to create a thin disk-shaped object with specified dimensions and properties for use in simulations.

2. How do I troubleshoot uniaxial anisotropy in "Make Disk"?

To troubleshoot uniaxial anisotropy in "Make Disk," you can check the following:

  • Ensure that the "Make Disk" command is being applied to the correct object or region in your simulation.
  • Check that the anisotropy constant and direction are specified correctly in the "Make Disk" command.
  • Verify that the coordinate system in your simulation is consistent with the anisotropy direction.
  • Double-check that the dimensions and orientation of the disk are correct.
If the issue persists, you may need to consult the OOMMF user manual or seek assistance from the OOMMF community forums.

3. Can I change the anisotropy properties after using "Make Disk"?

Yes, you can change the anisotropy properties of a disk object created with "Make Disk" by using the "Oxs_Anisotropy" command. This allows you to modify the anisotropy constant and direction of the disk, as well as add additional anisotropy terms if needed.

4. Why is my disk not exhibiting the expected uniaxial anisotropy behavior?

There could be several reasons why your disk is not showing the expected uniaxial anisotropy behavior, such as:

  • Incorrect input parameters, such as anisotropy direction or constant, in the "Make Disk" command.
  • Inconsistent coordinate system between the disk and other objects in the simulation.
  • Presence of other anisotropy terms or external fields that may be affecting the disk's behavior.
It is important to carefully check all input parameters and ensure consistency throughout the simulation.

5. Can I use "Make Disk" for non-uniform anisotropy?

No, "Make Disk" only allows for the creation of thin disks with uniform anisotropy. If you need to simulate a disk with non-uniform anisotropy, you can use the "Oxs_RectangularMesh" command to define a mesh with varying anisotropy properties and then use the "Oxs_RectangularMeshAtlas" command to convert it into an OOMMF object. Alternatively, you can also use the "Oxs_TransformRegion" command to apply anisotropy transformations to a pre-defined disk object.

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