MuMax3_Hysteresis_Loop_Example.txt

// Magnetic geometry of 128 nm x 32 nm x 30 nm.
// Unit cell size of 4 nm x 4 nm x 30 nm.

SetGridsize(128, 32, 30)
SetCellsize(4e-9, 4e-9, 30e-9)

Msat  = 800e3 // Saturation magnetisation (A/m).
Aex   = 13e-12 // Exchange energy constant (J/m).

// Gilbert damping can be set if needed. Example: alpha = 0.02
// Uniaxial anisotropy constant (J/m**3) can be set if needed. Example: Ku1 = 7.0e6
// Initial magnetization direction can also be randomized if you want. Example: m = randomMag().
// Initial magnetization direction in (x, y, z), also known as m0 can be set if prefered. Example: m = uniform(1, 0, 0)
// Interestingly, FreeLayerThickness can be set if needed. Check MuMax3 API reference.
// Anisotropy direction info can be added here if simulating a hard magnet. Example in x-direction: anisU = vector(1, 0, 0)
// Note that gyromagnetic ratio is not coded here since it is a value of 2.211e5 m/A/s by default in MuMax3.

m = randomMag()
relax() // High-energy states best minimized by relax()


Bmax  := 100.0e-3
Bstep :=  1.0e-3
MinimizerStop = 1e-6
TableAdd(B_ext)

// You can now save the output as an OVF file format for post processing of vector field. The website (https://mumax.ugent.be/mumax-view) accepts OVF1_TEXT formats for visualization in the browser.

for B:=0.0; B<=Bmax; B+=Bstep{
    B_ext = vector(B, 0, 0)
    minimize()   // small changes best minimized by minimize()
    tablesave()
    OutputFormat = OVF1_TEXT
    saveas(B_ext, "ovf1_text1")
}

for B:=Bmax; B>=-Bmax; B-=Bstep{
    B_ext = vector(B, 0, 0)
    minimize()   // small changes best minimized by minimize()
    tablesave()
    OutputFormat = OVF1_TEXT
    saveas(B_ext, "ovf1_text1")
}

for B:=-Bmax; B<=Bmax; B+=Bstep{
    B_ext = vector(B, 0, 0)
    minimize()   // small changes best minimized by minimize()
    tablesave()
    OutputFormat = OVF1_TEXT
    saveas(B_ext, "ovf1_text1")
}