Slonczewski STT (Mumax3 Example code)

[Amrit Kumar Mondal]

Dear All,
I am currently working on a project involving the manipulation of layer thicknesses, specifically the free layer, spacer layer, and fixed layer. However, I'm encountering some confusion regarding the code provided.

////////////////////////////////////  Mumax example code  //////////////////////////////////////
// geometry
sizeX := 160e-9
sizeY := 80e-9
sizeZ := 5e-9
Nx := 64
Ny := 32
setgridsize(Nx, Ny, 1)
setcellsize(sizeX/Nx, sizeY/Ny, sizeZ)
setGeom(ellipse(sizeX, sizeY))

// set up free layer
Msat  = 800e3
Aex   = 13e-12
alpha = 0.01
m     = uniform(1, 0, 0)

// set up spacer layer parameters
lambda       = 1
Pol          = 0.5669
epsilonprime = 0

// set up fixed layer polarization
angle := 20
px := cos(angle * pi/180)
py := sin(angle * pi/180)
fixedlayer = vector(px, py, 0)

// send current
Jtot := -0.008            // total current in A
area := sizeX*sizeY*pi/4
jc   := Jtot / area       // current density in A/m2
J = vector(0, 0, jc)

// schedule output & run
autosave(m, 100e-12)
tableautosave(10e-12)
run(1e-9)
///////////////////////////////////////////////////////////////////////////////////////////////////////////

I aim to vary the thickness of all layers within the range of 1 nm to 10 nm. Could you kindly offer guidance or assistance on how to execute this task within the provided code?

Thank you in advance.
               -------
Amrit Kumar Mondal

[Josh Lauzier]

Hi,

Mumax only explicitly models the free layer. You can adjust the thickness of the free layer by adjust SizeZ (keeping in mind to adjust Nz to keep a reasonable cellsize). There is also the Freelayerthickness parameter (by default it is determined from the meshsize).

For the fixed layer and spacer layer, you can only manipulate the parameters associated with them.

Best,
Josh L.

[Amrit Kumar Mondal]

Dear Josh,

Thank you for your assistance with my question.

From what I understand, I can adjust the free layer thickness by manipulating SizeZ, where the thickness of the free layer equals SizeZ.

Do you know of any model or simulation-based package that allows tuning of the spacer layer thickness as well?

      Thanks & Regards,

               ----------

    Amrit Kumar Mondal

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[Josh Lauzier]

Hi,

I am not sure, but I think maybe a multi-physics package like Comsol might be appropriate. I'm not sure if it can do everything you need. You might need to combine 2 packages, for instance using Comsol to model the spacer layer, and using the results as inputs into something like mumax.

Cheers,
Josh L.