def test_script(self):
system = oc.System(name="test_system")
system.mesh = oc.Mesh((0, 0, 0), (5, 5, 5), (1, 1, 1))
system.hamiltonian += oc.Exchange(1e-12)
system.hamiltonian += oc.Demag()
system.hamiltonian += oc.UniaxialAnisotropy(1e3, (0, 1, 0))
system.hamiltonian += oc.Zeeman((0, 1e6, 0))
system.dynamics += oc.Precession(2.211e5)
system.dynamics += oc.Damping(0.1)
system.m = lambda pos: (0, 1, 0)
script = system.script()
assert script[0] == "#"
assert script[-1] == "\n"
assert script.count("#") == 6
assert script.count("Specify") == 6
assert "Exchange" in script
assert "Demag" in script
assert "Zeeman" in script
assert "UniaxialAnisotropy" in script
assert "BoxAtlas" in script
assert "RectangularMesh" in script
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_missing_terms(self):
# Missing Gilbert damping alpha
self.system.dynamics = oc.Precession(gamma=2.2)
td = oc.TimeDriver()
script = td.script(self.system, t=1e-9, n=20)
assert "alpha 0" in script
assert "gamma_G 2.2" in script
# Missing gamma
self.system.dynamics = oc.Damping(alpha=5)
td = oc.TimeDriver()
script = td.script(self.system, t=1e-9, n=20)
assert "alpha 5" in script
assert "gamma_G 221100" in script
def test_stdprob5():
name = "stdprob5"
# Remove any previous simulation directories.
if os.path.exists(name):
shutil.rmtree(name)
# Geometry
lx = 100e-9 # x dimension of the sample(m)
ly = 100e-9 # y dimension of the sample (m)
lz = 10e-9 # sample thickness (m)
# Material (permalloy) parameters
Ms = 8e5 # saturation magnetisation (A/m)
A = 1.3e-11 # exchange energy constant (J/m)
# Dynamics (LLG + STT equation) parameters
gamma = 2.211e5 # gyromagnetic ratio (m/As)
alpha = 0.1 # Gilbert damping
ux = -72.35 # velocity in x direction
beta = 0.05 # non-adiabatic STT parameter
system = oc.System(name=name)
mesh = oc.Mesh(p1=(0, 0, 0),
p2=(100e-9, 100e-9, 10e-9),
cell=(5e-9, 5e-9, 5e-9))
system.mesh = mesh
system.hamiltonian = oc.Exchange(A) + oc.Demag()
def m_vortex(pos):
x, y, z = pos[0] / 1e-9 - 50, pos[1] / 1e-9 - 50, pos[2] / 1e-9
return (-y, x, 10)
system.m = df.Field(mesh, value=m_vortex, normalisedto=Ms)
md = oc.MinDriver()
md.drive(system)
system.dynamics += oc.Precession(gamma) + oc.Damping(alpha) + \
oc.STT(u=(ux, 0, 0), beta=beta)
td = oc.TimeDriver()
td.drive(system, t=8e-9, n=100)
mx = system.dt["mx"].as_matrix()
assert -0.03 < mx.max() < 0
assert -0.35 < mx.min() < -0.30
shutil.rmtree(name)
def macrospin():
"""Return a sytsem that represents a macrospin.
"""
p1 = (0, 0, 0)
p2 = (5e-9, 5e-9, 5e-9)
cell = (5e-9, 5e-9, 5e-9)
mesh = oc.Mesh(p1=p1, p2=p2, cell=cell)
system = oc.System(name="example-macrospin")
system.hamiltonian = oc.Zeeman(H=(0, 0, 5e6))
system.m = df.Field(mesh, value=(0, 0, 1), norm=8e6)
system.dynamics = oc.Precession(gamma=oc.gamma) + oc.Damping(alpha=0.05)
return system
def bar():
system = oc.System(name="example-bar")
shape = (100e-9, 30e-9, 30e-9)
d = 10e-9
mesh = oc.Mesh(p1=(0, 0, 0), p2=shape, cell=(d, d, d))
# Permalloy
A = 1e-12
H = (0, 0, 0) # no Zeeman field, but provide interaction as convenience
system.hamiltonian = oc.Exchange(A=A) + oc.Demag() + oc.Zeeman(H=H)
alpha = 0.2
system.dynamics = oc.Precession(gamma=oc.gamma0) + oc.Damping(alpha=alpha)
Ms = 8e6 # A/m
system.m = df.Field(mesh, value=(1, 0, 1), norm=Ms)
return system
def test_stdprobfmr():
name = "stdprobfmr"
# Remove any previous simulation directories.
if os.path.exists(name):
shutil.rmtree(name)
lx = ly = 120e-9 # x and y dimensions of the sample(m)
lz = 10e-9 # sample thickness (m)
dx = dy = dz = 10e-9 # discretisation in x, y, and z directions (m)
Ms = 8e5 # saturation magnetisation (A/m)
A = 1.3e-11 # exchange energy constant (J/m)
H = 8e4 * np.array([0.81345856316858023, 0.58162287266553481, 0.0])
alpha = 0.008 # Gilbert damping
gamma = 2.211e5
mesh = oc.Mesh(p1=(0, 0, 0), p2=(lx, ly, lz), cell=(dx, dy, dz))
system = oc.System(name="stdprobfmr")
system.hamiltonian = oc.Exchange(A) + oc.Demag() + oc.Zeeman(H)
system.dynamics = oc.Precession(gamma) + oc.Damping(alpha)
system.m = df.Field(mesh, value=(0, 0, 1), norm=Ms)
md = oc.MinDriver()
md.drive(system)
H = 8e4 * np.array([0.81923192051904048, 0.57346234436332832, 0.0])
system.hamiltonian.zeeman.H = H
T = 20e-9
n = 4000
td = oc.TimeDriver()
td.drive(system, t=T, n=n)
t = system.dt['t'].as_matrix()
my = system.dt['mx'].as_matrix()
psd = np.log10(np.abs(scipy.fftpack.fft(my))**2)
f_axis = scipy.fftpack.fftfreq(4000, d=20e-9/4000)
shutil.rmtree(name)
def macrospin():
"""Return a sytsem that represents a macrospin."""
# define macro spin (i.e. one discretisation cell)
p1 = (0, 0, 0) # all lengths in metre
p2 = (5e-9, 5e-9, 5e-9)
cell = (5e-9, 5e-9, 5e-9)
mesh = oc.Mesh(p1=p1, p2=p2, cell=cell)
initial_m = (1, 0, 0) # vector in x direction
Ms = 8e6 # magnetisation saturation (A/m)
m = df.Field(mesh, value=initial_m, norm=Ms)
zeeman = oc.Zeeman(H=(0, 0, 5e6)) # external magnetic field (A/m)
gamma = 2.211e5 # gyrotropic ratio
alpha = 0.05 # Gilbert damping
runid = "example-macrospin"
system = oc.System(name=runid)
system.hamiltonian = zeeman
system.m = m
system.dynamics = oc.Precession(gamma) + oc.Damping(alpha)
return system
if os.path.exists(name):
shutil.rmtree(name)
L = 30e-9 # (m)
cellsize = (10e-9, 15e-9, 5e-9) # (m)
mesh = oc.Mesh((0, 0, 0), (L, L, L), cellsize)
system = oc.System(name=name)
A = 1.3e-11 # (J/m)
H = (1e6, 0.0, 2e5)
system.hamiltonian = oc.Exchange(A=A) + oc.Zeeman(H=H)
gamma = 2.211e5 # (m/As)
alpha = 0.02
system.dynamics = oc.Precession(gamma) + oc.Damping(alpha)
Ms = 8e5 # (A/m)
system.m = df.Field(mesh, value=(0.0, 0.25, 0.1), norm=Ms)
td = oc.TimeDriver()
td.drive(system, t=25e-12, n=25) # updates system.m in-place
td.drive(system, t=15e-12, n=15)
td.drive(system, t=5e-12, n=10)
md = oc.MinDriver()
md.drive(system)
system.hamiltonian.zeeman.H = (0.0, 0.0, 1.0e6)
td.drive(system, t=5e-12, n=5)
md.drive(system)
def test_script(self):
for alpha in self.valid_args:
damping = oc.Damping(alpha)
with pytest.raises(NotImplementedError):
damping._script()
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 = oc.Mesh((0, 0, 0), (L, d, th), cellsize)
system = oc.System(name=name)
A = 1.3e-11 # (J/m)
system.hamiltonian = oc.Exchange(A) + oc.Demag()
gamma = 2.211e5 # (m/As)
alpha = 0.02
system.dynamics = oc.Precession(gamma) + oc.Damping(alpha)
Ms = 8e5 # (A/m)
system.m = df.Field(mesh, value=(1, 0.25, 0.1), norm=Ms)
md = oc.MinDriver()
md.drive(system) # updates system.m in-place
dirname = os.path.join(name, "")
miffilename = os.path.join(name, "{}.mif".format(name))
assert os.path.exists(dirname)
assert os.path.isfile(miffilename)
omf_files = list(glob.iglob("{}/*.omf".format(name)))
odt_files = list(glob.iglob("{}/*.odt".format(name)))
assert len(omf_files) == 2
omffilename = os.path.join(name, "m0.omf")
assert omffilename in omf_files
assert len(odt_files) == 1
shutil.rmtree(name)
H = (-24.6e-3/oc.mu0, 4.3e-3/oc.mu0, 0)
system.hamiltonian += oc.Zeeman(H)
td = oc.TimeDriver()
td.drive(system, t=1e-9, n=200)
dirname = os.path.join(name, "")
miffilename = os.path.join(name, "{}.mif".format(name))
assert os.path.exists(dirname)
assert os.path.isfile(miffilename)
omf_files = list(glob.iglob("{}/*.omf".format(name)))
odt_files = list(glob.iglob("{}/*.odt".format(name)))
assert len(omf_files) == 201
omffilename = os.path.join(name, "m0.omf")
assert omffilename in omf_files
assert len(odt_files) == 1
myplot = system.dt.plot("t", "my")
figfilename = os.path.join(name, "stdprob4-t-my.pdf")
myplot.figure.savefig(figfilename)
assert os.path.isfile(figfilename)
t = system.dt["t"].as_matrix()
my = system.dt["my"].as_matrix()
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)
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)