Creation of High Ku region at boundary of circular nanotrack

[RAVI SHANKAR VERMA 22915022]

Dear all,

I tried for the creation of high Ku region at the boundary of free layer of a MTJ. The MTJ is composed of a fixed layer as a spin polarizer with vortex-like magnetization having 253 regions (as shown in attached figure) to stop the skyrmion inhalation at the boundary. So I can use it as skymion based spin torque nano oscillator.

I wrote code for circular motion of skyrmion in the free layer around  and high Ku region. The code is working very well but effect of high Ku region at boundary did not observed.

Kindly let me know the changes that are required in the following code.

setgridsize(200, 200, 1)
setcellsize(1e-9, 1e-9, 0.6e-9)

a:= ellipsoid(110e-9, 110e-9, 0.6e-9)
b:= ellipsoid(95e-9, 95e-9, 0.6e-9)
c:= a.sub(b)
d:= ellipsoid(95e-9, 95e-9, 0.6e-9)
setgeom(d.add(c))
saveas(geom,"MTJ")

defregion(254, a.sub(b))

ku1.setregion(254, 1.7e6)
anisU.setregion(254, vector(0,0,1))


// set up free layer
Msat = 580e3
Aex = 15e-12
Dind = 3e-3
Ku1 = 0.8e6
AnisU = vector(0,0,1)
alpha = 0.3

m = neelskyrmion(1, -1).transl(-25e-9,0,0)

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

// set up fixed layer polarization
NSectors := 253
sliceOfPie := xrange(0, inf).sub(xrange(0, inf).rotz(2 * pi / NSectors))
for i := 0; i < NSectors; i++ {
angle := i * 2 * pi / NSectors
defregion(i, sliceOfPie.Rotz(angle))
FixedLayer.SetRegion(i, vector(-sin(angle), cos(angle), 0))
}

// send current
J = vector(0, 0, 6e10)

// schedule output & run
autosave(m, 1e-11)
tableautosave(1e-11)
tableAdd(ext_bubblepos)
run(100e-9)

Thanks

[Josh Lauzier]

Hi,

When you do

Ku1 = 0.8e6

AnisU = vector(0,0,1)

This sets it for the entire simulation (including overriding your outer region 254 that you set previously). You need to either define it by using a region, or put the portion defining the high-Ku region afterwards.

Best,

Josh L.

[马晓萍]

Hi all,

I'm encountering a similar issue now.

When I define the high K region before setting the fixedlayer, the high K region doesn't show up.
However, if I set the fixedlayer first and then define the high K region, the fixed layer becomes affected, as illustrated in the figure.

Thank you in advance for your help and solutions!

[Josh Lauzier]

Hi,

Please post the script (or both variations of the script) that you're having issues with. It makes it much easier to diagnose.

Best,
Josh L.