RKKY coupling between FM with different structure

[Hying]

Dear all,
From mumax3 workshop, the prefactor and shift functions are defined as following for FM(1nm)/SL(1nm)/FM(1nm): 
prefactorZ := Const( (2 * AFMAex) / (cellsize*cellsize*Ms))
up := Mul(prefactorZ,Mul(Add(Mul(Const(-1),m),Shifted(m,0,0, 2)),Shifted(Const(1),0,0,2)))
down :=  Mul(prefactorZ,Mul(Add(Mul(Const(-1),m),Shifted(m,0,0,-2)),Shifted(Const(1),0,0,-2)))
freelayerthickness=2e-9
setgridsize(256,64,3)
setcellsize(1e-9,1e-9,1e-9)
// define 2 layers
defregion(1,layer(2))
defregion(2,layer(0))
setgeom(layer(0).add(layer(2)))

I’m not sure that How should I modify the up and down functions for my structure: FM(2nm)/SL(1nm)/FM(2nm):
freelayerthickness=4e-9
setgridsize(8,8,5)
setcellsize(3.75e-9,3.75e-9,1e-9)
// define 2 layers
top:=cylinder(30e-9,2e-9).transl(0,0,1.5e-9)
bottom:=cylinder(30e-9,2e-9).transl(0,0,-1.5e-9)
defRegion(1, bottom)
defRegion(2, top)
setgeom(top.add(bottom))
 
Thank you very much in advance for any help!
Best, Hying

[Josh Lauzier]

Hi,

You would want to mask the custom parts to only effect the two layers on either side of the spacer, as discussed in these previous discussions. So for your structure, something like:

up := Mul(prefactorZ,Mul(Add(Mul(Const(-1),m),Shifted(m,0,0, 2)),Shifted(Const(1),0,0,2)))
down :=  Mul(prefactorZ,Mul(Add(Mul(Const(-1),m),Shifted(m,0,0,-2)),Shifted(Const(1),0,0,-2))) 

Maskeddown:= Masked( layer(1),down)
Maskedup:= Masked (layer(3),up)
AddFieldTerm(Maskeddown)
AddFieldTerm(MaskedUp)

(Actually, in your special case, you technically don't actually even need to bother to do this. There is nothing for layer 0 and layer 4 to couple to, so you can get away with being lazy. But if you had anymore than 5 layers, this is how you would do it)

Best,
Josh L.

[Hying]

Hi Josh,

Thank you very much for your reply!

I did the test, and it's the same as you said. I got the same switching time for the simulations. There is nothing for layer 0 and layer4 to couple!

 
Thank you again and best wishes!

Hying