/*****************************************************************  

  Description: 

   This mumax3 script demonstrates the creep motion of domain
   walls in the presence of a driving force, thermal fluctuations,
   and material disorder.

   This file is written for the mumax3 workshop organised for the 
   spintronic seminar series in the summer of 2020. For more 
   information go to https://www.mumax.ugent.be/mumax3-workshop
  
  Authors:

   Dr. Jonathan Leliaert (jonathan.leliaert@ugent.be)
   Dr. Jeroen Mulkers    (jeroen.mulkers@ugent.be)

******************************************************************/

SetMesh(128, 32, 1, 3.125e-09, 3.125e-09, 10e-09, 0, 0, 0)
Msat = 800e3
Aex = 1e-11
alpha = 0.1

m=twodomain(1,0,0,  0,1,0,  -1,0,0) 

//remove edge charges
BoundaryRegion := 0
MagLeft        := 1
MagRight       := -1
ext_rmSurfaceCharge(BoundaryRegion, MagLeft, MagRight)

relax()

// define grains with region number 0-255
grainSize  := 40e-9  
randomSeed := 1234567
maxRegion  := 255
ext_makegrains(grainSize, maxRegion, randomSeed)

// set random anisotropy per region
for i:=0; i<maxRegion; i++{
	// random uniaxial anisotropy direction on the unit sphere
	axis  := vector(randNorm(), randNorm(), randNorm())
	// note: axes are normalized by mumax
	AnisU.SetRegion(i, axis)     

	// random 10% anisotropy variation
	K := 1e3
	Ku1.SetRegion(i, K + randNorm() * 0.1 * K)
}

// reduce exchange coupling between grains by 10%
for i:=0; i<maxRegion; i++{
	for j:=i+1; j<maxRegion; j++{
		ext_ScaleExchange(i, j, 0.9)
	}
}

//set temperature and solver with adaptive timestepping

temp=300
Thermseed(12345) 
setsolver(5)
fixdt=0

//driving force: spin transfer torque
Pol=0.4
xi=0.2
j=vector(-1e12,0,0)

//keep wall centered: moving window
ext_centerwall(0)

//schedule output 
tableadd(ext_dwxpos)
tableautosave(1e-10) 


run(5e-7)