def test_script(self):
system = mc.System(name="test_system")
system.hamiltonian += mc.Exchange(1e-12)
system.hamiltonian += mc.Demag()
system.hamiltonian += mc.UniaxialAnisotropy(1e3, (0, 1, 0))
system.hamiltonian += mc.Zeeman((0, 1e6, 0))
system.dynamics += mc.Precession(2.211e5)
system.dynamics += mc.Damping(0.1)
mesh = mc.Mesh((0, 0, 0), (5, 5, 5), (1, 1, 1))
system.m = df.Field(mesh, dim=3, value=(0, 1, 0), norm=1)
script = system._script
assert script[-1] == "\n"
assert "mu0mm" in script
assert "SetGridSize(5, 5, 5)" in script
assert "SetCellSize(1, 1, 1)" in script
assert "Aex=1e-12" in script
assert "enabledemag=true" in script
assert "B_ext=vector(0*mu0mm,1000000.0*mu0mm,0*mu0mm)" in script
assert "Ku1=1000.0" in script
assert "Ku2=0" in script
assert "anisu=vector(0,1,0)" in script
return None
def minimise_system_energy(L, m_init):
N = 16 # discretisation in one dimension
cubesize = 100e-9 # cube edge length (m)
cellsize = cubesize / N # discretisation in all three dimensions.
lex = cubesize / L # exchange length.
Km = 1e6 # magnetostatic energy density (J/m**3)
Ms = np.sqrt(2 * Km / mc.mu0) # magnetisation saturation (A/m)
A = 0.5 * mc.mu0 * Ms**2 * lex**2 # exchange energy constant
K = 0.1 * Km # Uniaxial anisotropy constant
u = (0, 0, 1) # Uniaxial anisotropy easy-axis
p1 = (0, 0, 0) # Minimum sample coordinate.
p2 = (cubesize, cubesize, cubesize) # Maximum sample coordinate.
cell = (cellsize, cellsize, cellsize) # Discretisation.
mesh = mc.Mesh(p1=(0, 0, 0),
p2=(cubesize, cubesize, cubesize),
cell=(cellsize, cellsize, cellsize))
# Remove any previous simulation directories.
if os.path.exists(name):
shutil.rmtree(name)
system = mc.System(name=name)
system.hamiltonian = mc.Exchange(A) + mc.UniaxialAnisotropy(K, u) + \
mc.Demag()
system.m = df.Field(mesh, value=m_init, norm=Ms)
md = mc.RelaxDriver()
md.drive(system)
if os.path.exists(name):
shutil.rmtree(name)
return system
def setup(self):
self.system = oc.System(name='tds')
mesh = oc.Mesh((0, 0, 0),
(100e-9, 100e-9, 10e-9),
(10e-9, 10e-9, 10e-9))
self.system.hamiltonian += oc.Exchange(1.5e-11)
self.system.hamiltonian += oc.Demag()
self.system.dynamics += oc.Precession(2.211e5)
self.system.dynamics += oc.Damping(0.02)
self.system.m = df.Field(mesh, value=(0, 1, 0), norm=8e5)
def test_script(self):
demag = mc.Demag()
script = demag._script
assert script.count("\n") == 3
assert script[0:2] == "//"
assert script[-1] == "\n"
lines = script.split("\n")
assert len(lines) == 4
assert lines[0] == "// Demag"
assert lines[1] == "enabledemag=true"
def test_skyrmion():
name = "skyrmion"
# Remove any previous simulation directories.
if os.path.exists(name):
shutil.rmtree(name)
mesh = mc.Mesh(p1=(-50e-9, -50e-9, 0),
p2=(50e-9, 50e-9, 10e-9),
cell=(5e-9, 5e-9, 5e-9))
system = mc.System(name="skyrmion")
system.hamiltonian = mc.Exchange(A=1.6e-11) + \
mc.DMI(D=4e-3, crystalclass="cnv") + \
mc.UniaxialAnisotropy(K1=0.51e6, K2=0.1, u=(0, 0, 1)) + \
mc.Demag() + \
mc.Zeeman(H=(0, 0, 2e5))
Ms = 1.1e6
def Ms_fun(pos):
x, y, z = pos
if (x**2 + y**2)**0.5 < 50e-9:
return Ms
else:
return 0
def m_init(pos):
x, y, z = pos
if (x**2 + y**2)**0.5 < 10e-9:
return (0, 0.1, -1)
else:
return (0, 0.1, 1)
system.m = df.Field(mesh, value=m_init, norm=Ms_fun)
md = mc.MinDriver()
md.drive(system)
# Check the magnetisation at the sample centre.
assert system.m((0, 0, 0))[2] / Ms < -0.97
# Check the magnetisation at the sample edge.
assert system.m((50e-9, 0, 0))[2] / Ms > 0
shutil.rmtree(name)
#import oommfc as mc import mumaxc as mc import discretisedfield as df L = 10e-9 d = 1e-9 Ms = 8e6 # saturation magnetisation (A/m) A = 1e-12 # exchange energy constant (J/m) H = (5e6, 0, 0) # external magnetic field in the x-direction (A/m) gamma = 2.211e5 # gamma parameter (m/As) alpha = 0.2 # Gilbert damping mesh = mc.Mesh(p1=(0, 0, 0), p2=(L, L, L), cell=(d, d, d)) system = mc.System(name='example2') system.hamiltonian = mc.Exchange(A=A) + mc.Demag() + mc.Zeeman(H=H) system.dynamics = mc.Precession(gamma=gamma) + mc.Damping(alpha=alpha) system.m = df.Field(mesh, value=(0, 0, 1), norm=Ms) td = mc.TimeDriver() td.drive(system, t=1e-9, n=10, overwrite=True) mx, my, mz = system.m.average assert mx > my assert mx > mz print(system.m.average)
def test_stdprob4():
name = "stdprob4"
# Remove any previous simulation directories.
if os.path.exists(name):
shutil.rmtree(name)
L, d, th = 500e-9, 125e-9, 3e-9 # (m)
cellsize = (5e-9, 5e-9, 3e-9) # (m)
mesh = mc.Mesh((0, 0, 0), (L, d, th), cellsize)
system = mc.System(name=name)
A = 1.3e-11 # (J/m)
system.hamiltonian = mc.Exchange(A) + mc.Demag()
gamma = 2.211e5 # (m/As)
alpha = 0.02
system.dynamics = mc.Precession(gamma) + mc.Damping(alpha)
Ms = 8e5 # (A/m)
system.m = df.Field(mesh, value=(1, 0.25, 0.1), norm=Ms)
md = mc.MinDriver()
md.drive(system) # updates system.m in-place
dirname = os.path.join(name, "drive-{}".format(system.drive_number - 1))
mx3filename = os.path.join(dirname, "{}.mx3".format(name))
assert os.path.exists(dirname)
assert os.path.isfile(mx3filename)
omf_files = list(glob.iglob("{}/**/*.o*f".format(dirname), recursive=True))
txt_files = list(glob.iglob("{}/**/*.txt".format(dirname), recursive=True))
assert len(omf_files) == 3
omffilename = os.path.join(dirname, "m0.omf")
assert omffilename in omf_files
assert len(txt_files) == 2
shutil.rmtree(name)
H = (-24.6e-3 / mc.mu0, 4.3e-3 / mc.mu0, 0)
system.hamiltonian += mc.Zeeman(H)
td = mc.TimeDriver()
td.drive(system, t=1e-9, n=200)
dirname = os.path.join(name, "drive-{}".format(system.drive_number - 1))
mx3filename = os.path.join(dirname, "{}.mx3".format(name))
assert os.path.exists(dirname)
assert os.path.isfile(mx3filename)
omf_files = list(glob.iglob("{}/**/*.o*f".format(dirname), recursive=True))
txt_files = list(glob.iglob("{}/**/*.txt".format(dirname), recursive=True))
assert len(omf_files) == 202
omffilename = os.path.join(dirname, "m0.omf")
assert omffilename in omf_files
assert len(txt_files) == 2
t = system.dt["t"].values
my = system.dt["my"].values
assert abs(min(t) - 5e-12) < 1e-20
assert abs(max(t) - 1e-9) < 1e-20
# Eye-norm test.
assert 0.7 < max(my) < 0.8
assert -0.5 < min(my) < -0.4
shutil.rmtree(name)