def run_simulation(periodic=False, use_hlib=False):
phi_BEM = (nmag.default_hmatrix_setup if use_hlib else None)
if periodic:
pts = [[i*(15.0 + 0.1), 0, 0] for i in (-3, -2, -1, 1, 2, 3)]
pbc = nmag.SetLatticePoints(vectorlist=pts, scalefactor=nm)
sim = nmag.Simulation("periodic", periodic_bc=pbc.structure,
phi_BEM=phi_BEM)
else:
sim = nmag.Simulation("full", phi_BEM=phi_BEM)
mat = nmag.MagMaterial("Py",
Ms=SI(0.86e6, "A/m"),
exchange_coupling=SI(13e-12, "J/m"),
llg_damping=0.5)
mesh_file = "periodic.nmesh.h5" if periodic else "full.nmesh.h5"
sim.load_mesh(mesh_file, [("mesh", mat)], unit_length=nm)
sim.set_m([1, 1, 1])
sim.relax(do=[("exit", at("time", 0.5*ns))],
save=[("averages", every("time", 10*ps))])
v = (1.0e-9, dz, -dy)
vn = (1.0e-9**2 + dy*dy + dz*dz)**0.5
return tuple(vi/vn for vi in v)
sim.set_m(m0)
sim.set_H_ext([0, 0, 0], SI("A/m"))
# Direction of the polarization
sim.model.quantities["sl_fix"].set_value(Value([0, 1, 0]))
# Current density
sim.model.quantities["sl_current_density"].set_value(Value(SI(0.1e12, "A/m^2")))
if do_relaxation:
print "DOING RELAXATION"
sim.relax(save=[("fields", at("time", 0*ps) | at("convergence"))])
sim.save_m_to_file(relaxed_m)
sys.exit(0)
else:
print "DOING DYNAMICS"
sim.load_m_from_h5file(relaxed_m)
sim.set_params(stopping_dm_dt=0*degrees_per_ns)
sim.relax(save=[("averages", every("time", 5*ps))],
do=[("exit", at("time", 10000*ps))])
#ipython()
import nmag
from nmag import SI, si
# Create the simulation object
sim = nmag.Simulation()
# Define the magnetic material (data from OOMMF materials file)
Fe = nmag.MagMaterial(name="Fe",
Ms=SI(1700e3, "A/m"),
exchange_coupling=SI(21e-12, "J/m"),
anisotropy=nmag.cubic_anisotropy(axis1=[1, 0, 0],
axis2=[0, 1, 0],
K1=SI(48e3, "J/m^3")))
# Load the mesh
sim.load_mesh("cube.nmesh", [("cube", Fe)], unit_length=SI(1e-9, "m"))
# Set the initial magnetisation
sim.set_m([0, 0, 1])
# Launch the hysteresis loop
Hs = nmag.vector_set(direction=[1.0, 0, 0.0001],
norm_list=[0, 1, [], 19, 19.1, [], 21, 22, [], 50],
units=0.001 * si.Tesla / si.mu0)
from nmag import every, at
sim.hysteresis(Hs,
save=[('averages', 'fields', at('stage_end')),
('restart', at('stage_end') | every('step', 1000))])
import nmag
from nmag import SI, every, at
# define magnetic material
Py = nmag.MagMaterial(name="Py",
Ms=SI(1e6,"A/m"),
exchange_coupling=SI(13.0e-12, "J/m")
)
#create simulation object
sim = nmag.Simulation()
# load mesh
sim.load_mesh("prism.nmesh.h5", [("no-periodic", Py)], unit_length=SI(1e-9,"m") )
# set initial magnetisation
sim.set_m([1.,1.,1.])
# loop over the applied field
s = SI(1,"s")
sim.relax(save=[('averages','fields', every('time',5e-12*s) | at('convergence'))])
import nmag
from nmag import SI, at
#create simulation object
sim = nmag.Simulation()
# define magnetic material
Py = nmag.MagMaterial(name="Py",
Ms=SI(1e6,"A/m"),
exchange_coupling=SI(13.0e-12, "J/m"))
# load mesh: the mesh dimensions are scaled by 0.5 nm
sim.load_mesh("ellipsoid.nmesh.h5",
[("ellipsoid", Py)],
unit_length=SI(1e-9,"m"))
# set initial magnetisation
sim.set_m([1.,0.,0.])
Hs = nmag.vector_set(direction=[1.,0.01,0],
norm_list=[ 1.00, 0.95, [], -1.00,
-0.95, -0.90, [], 1.00],
units=1e6*SI('A/m'))
# loop over the applied fields Hs
sim.hysteresis(Hs, save=[('restart','fields', at('convergence'))])
anis_B = nmag.uniaxial_anisotropy(axis=[1, 0, 0], K1=SI(0.1e6, "J/m^3"))
mat_B = nmag.MagMaterial(name="B",
Ms=SI(0.5e6, "A/m"),
exchange_coupling=SI(10.0e-12, "J/m"),
anisotropy=anis_B,
llg_damping=0.1)
# Create the simulation object
sim = nmag.Simulation()
# Set the coupling between the two magnetisations
sim.set_local_magnetic_coupling(mat_A, mat_B, SI(-1.0e-5, "N/A^2"))
# Load the mesh
sim.load_mesh("thinfilm.nmesh.h5", [("mesh", [mat_A, mat_B])], unit_length=1*nm)
# Set additional parameters for the time-integration
sim.set_params(stopping_dm_dt=1*degrees_per_ns,
ts_rel_tol=1e-6, ts_abs_tol=1e-6)
sim.set_m([1, 0, 0], 'm_A') # Set the initial magnetisation
sim.set_m([-1, 0, 0], 'm_B')
Hs = vector_set(direction=[0.01, 0.01, 1],
norm_list=[1.0, 0.95, [], -1.0],
units=SI(1e6, "A/m"))
sim.hysteresis(Hs, save=[('averages', at('convergence'))])
#sim.hysteresis(Hs, save=[('averages', every('time', 1e5*ps) | at('convergence'))])
from nmag import SI, every, at
sim = nmag.Simulation()
# define magnetic material Cobalt (data from OOMMF materials file)
Co = nmag.MagMaterial(name="Co",
Ms=SI(1400e3, "A/m"),
exchange_coupling=SI(30e-12, "J/m"),
anisotropy=nmag.uniaxial_anisotropy(axis=[0,0,1], K1=SI(520e3, "J/m^3")))
# define magnetic material Permalley
Py = nmag.MagMaterial(name="Py",
Ms=SI(860e3,"A/m"),
exchange_coupling=SI(13.0e-12, "J/m"))
# load mesh
sim.load_mesh("two_cubes.nmesh.h5",
[("cube1", Py),("cube2", Co)],
unit_length=SI(1e-9,"m")
)
# set initial magnetisation along the
# positive x axis for both cubes, slightly off in z-direction
sim.set_m([0.999847695156, 0, 0.01745240643731])
ns = SI(1e-9, "s") # corresponds to one nanosecond
sim.relax(save = [('averages', every('time', 0.01*ns)),
('fields', every('time', 0.05*ns) | at('convergence'))])
# define magnetic material
Py = nmag.MagMaterial( name="Py",
Ms=SI(795774,"A/m"),
exchange_coupling=SI(13.0e-12, "J/m")
)
# load mesh: the mesh dimensions are scaled by 100nm
sim.load_mesh( "../example_vortex/nanodot.nmesh.h5",
[("cylinder", Py)],
unit_length=SI(100e-9,"m")
)
# set initial magnetisation
sim.set_m([1.,0.,0.])
Hs = nmag.vector_set( direction=[1.,0.,0.],
norm_list=[12.0, 7.0, [], -200.0],
units=1e3*SI('A/m')
)
# loop over the applied fields Hs
sim.hysteresis(Hs,
save=[('averages', at('convergence')),
('fields', at('convergence')),
('restart', at('convergence'))
]
)
s = FDSimulation(do_demag=True)
s.set_params(stopping_dm_dt=20 * degrees_per_ns)
nm = SI(1e-9, "m")
def rectangle(pos):
# if (pos[0] >=10e-9 and pos[0] <= 20e-9 and
# pos[1] >=10e-9 and pos[1] <= 20e-9):
return "magnetic"
# else:
# return None
s.create_mesh([5, 5, 1], [5.0 * nm, 5.0 * nm, 3.0 * nm], mat_Py, regions=rectangle)
s.set_m([1, 1, 1])
Hs = nmag.vector_set(
direction=[1.0, 1.0, 1.0], norm_list=[1.00, 0.95, [], 0.1, 0.09, [], -0.1, -0.15, [], -1.00], units=1e6 * SI("A/m")
)
s.hysteresis(Hs, save=[("field_m", at("time", SI(0, "s")) | at("convergence"))])
# Process the results
NCOL = os.path.join(os.path.dirname(os.path.abspath(nmag.__file__)), "../../bin/ncol")
os.system(NCOL + " run_fdsimulation H_ext_0 H_ext_1 H_ext_2 M_Py_0 M_Py_1 M_Py_2 > fd.dat")
os.system("gnuplot plot.gnp")
import nmag
from nmag import SI, every, at
mat_Py1 = nmag.MagMaterial(name="Py1",
Ms=SI(0.86e6,"A/m"),
exchange_coupling=SI(13.0e-12, "J/m"),
llg_damping=0.5)
mat_Py2 = nmag.MagMaterial(name="Py2",
Ms=SI(0.86e6,"A/m"),
exchange_coupling=SI(13.0e-12, "J/m"),
llg_damping=0.5)
#Example 1: both materials have same magnetisation
sim = nmag.Simulation()
sim.load_mesh("sphere_in_box.nmesh.h5",
[("Py1", mat_Py1),("Py2", mat_Py2)],
unit_length=SI(15e-9,"m"))
sim.set_m([1,0,0])
sim.relax(save = [('averages','fields','restart', every('step', 1000) | at('convergence'))])
unit_length=SI(1e-9, 'm'))
# set initial magnetisation
sim.set_m([0, 0, 1])
def my_save(sim):
# only save these Terms and Subfields
H_ext = sim.get_subfield_average_siv('H_ext')
print('Save fields of stage %d with H_ext %s' %(sim.stage, str(H_ext)))
sim.save_data(fields=['id', 'time', 'step', 'stage_time', 'stage_step', 'H_ext', 'M', 'm'])
def my_stage(sim):
# run the function before every stage start
H_ext = sim.get_subfield_average_siv('H_ext')
print('Set new H_ext of stage %d with H_ext %s' %(sim.stage, str(H_ext)))
def set_H(position):
x = position[0]
y = position[1]
z = position[2]
return H_ext
sim.set_H_ext(set_H, unit=SI(1,'A/m'))
# start time
start_time = time.time()
# start hysteresis
sim.hysteresis(Hs, save=[(my_save, at('convergence'))],
do=[(my_stage, every('stage', 1) & at('stage_step', 0))])
# print simulate time
use_time = (time.time() - start_time) / 60
print('Use Time %f min' % use_time)
u = min(1.0, max(0.0, (x - x0) / (x1 - x0)))
angle = math.pi * (1.0 - u)
return [math.cos(angle), math.sin(angle), 0]
def m0_FePt(r):
return m0_Py(r)
def save_m(s):
s.save_restart_file(relaxed_m_file)
s = simulation(
sim_name="relax",
damping_Py=1.0,
damping_FePt=1.0,
initial_m=[m0_Py, m0_FePt],
save=[("averages", every(1000, "step")), ("fields", at("step", 0) | at("stage_end"))],
do=[(save_m, at("stage_end"))],
)
del s
def set_current(j):
def j_setter(sim):
sim.set_current_density([j, 0.0, 0.0], unit=SI("A/m^2"))
return j_setter
ns = SI(1e-9, "s")
simulation(
sim_name="stt",
sim.load_mesh(meshfile, [("Py", mat_Py)],unit_length=SI(1e-9,"m"))
import math
angle_deg = 45
angle_rad = angle_deg/360.*2*math.pi
sim.set_m([math.cos(angle_rad), 0, math.sin(angle_rad)])
sim.set_params(ts_rel_tol=1e-06 , ts_abs_tol=1.0e-06,stopping_dm_dt = 10*si.degrees_per_ns)
ps = SI(1e-12, "s")
time_initialising += time.time()
time_loop = -time.time()
sim.relax(save = [('averages', every('time', 25*ps)|at('convergence')),
('fields',at('convergence'))])
time_loop += time.time()
time_simulating = time_loop - nmag.timing['save_data']
print "Setup took %g seconds" % time_initialising
print "Simulation loop took %g seconds" % time_loop
print "Writing data took: %g seconds" % nmag.timing['save_data']
print "Timestepper took: %g seconds" % time_simulating
print "Total time: %g seconds" % time_total
def out(line, header=False, file="bigbar_timings.log"):
import os
if header and os.path.exists(file): return
f = open(file, "a")
# Max Apply Field
H_max = 2*ku_hard*1e4/ms_hard
H_max = H_max*1e3/(4*math.pi) # koe to A/m
print('H_max %f' % H_max)
# set initial magnetisation
sim.set_m([0, 0, 1])
sim.set_params(stopping_dm_dt=2*degrees_per_ns)
def my_save(sim):
sim.save_data(fields=['id', 'time', 'step', 'stage_time', 'stage_step', 'H_ext', 'M', 'm'])
# save initial data
sim.relax(save=[(my_save, at('convergence'))])
# make H_ext = -H_max where y > 10
def set_H(position):
# positions unit is nm
x = position[0] / 1e-9
y = position[1] / 1e-9
z = position[2] / 1e-9
if y < 10:
return [0, 0, 0]
return [0, 0, -H_max]
sim.set_H_ext(set_H, unit=SI(1, 'A/m'))
sim.relax(save=[(my_save, at('convergence'))])
print('------make H_ext reserve------')
llg_damping=1.0)
# load mesh
sim.load_mesh('%s'%mesh_file,
[('Mat_Hard', Mat_Hard),('Mat_Soft', Mat_Soft)],
unit_length=SI(1e-9, 'm'))
sim.set_m([0,0,1])
H_max = 17 * 1e3 * 1e3/(4*math.pi) # koe to A/m
Hs = nmag.vector_set(direction=[0, 0, 1], norm_list=[-1.0, 1.0], units=H_max*SI('A/m'))
def my_save(sim):
# only save M, m, H_ext
sim.save_data(fields=['M', 'm', 'H_ext'])
def print_time(sim):
sim_time = float(sim.time/SI(1e-12, 's'))
print('----SIM Time %f ps----' % sim_time)
# start time
start_time = time.time()
sim.hysteresis(Hs, save=[(my_save, at('convergence'))],
do=[(print_time, every('time',SI(50e-12, 's')) | at('convergence'))])
use_time = (time.time() - start_time) / 60
print('Use Time %f min' % use_time)
import nmag
from nmag import SI, si
# Create the simulation object
sim = nmag.Simulation()
# Define the magnetic material (data from OOMMF materials file)
Fe = nmag.MagMaterial(name="Fe",
Ms=SI(1700e3, "A/m"),
exchange_coupling=SI(21e-12, "J/m"),
anisotropy=nmag.cubic_anisotropy(axis1=[1, 0, 0],
axis2=[0, 1, 0],
K1=SI(48e3, "J/m^3")))
# Load the mesh
sim.load_mesh("cube.nmesh", [("cube", Fe)], unit_length=SI(1e-9, "m"))
# Set the initial magnetisation
sim.set_m([0, 0, 1])
# Launch the hysteresis loop
Hs = nmag.vector_set(direction=[1.0, 0, 0.0001],
norm_list=[0, 1, [], 19, 19.1, [], 21, 22, [], 50],
units=0.001*si.Tesla/si.mu0)
from nmag import every, at
sim.hysteresis(Hs, save=[('averages', 'fields', at('stage_end')),
('restart', at('stage_end') | every('step', 1000))])
disturb_duration = 1 * ps
m0_filename = "m0.h5"
def simulate_nanowire(name, damping):
permalloy = nmag.MagMaterial("Py", Ms=SI(0.86e6, "A/m"), exchange_coupling=SI(13e-12, "J/m"), llg_damping=damping)
s = nmag.Simulation(name)
s.load_mesh("cylinder.nmesh.h5", [("nanopillar", permalloy)], unit_length=nm)
return s
s = simulate_nanowire("relaxation", 0.5)
s.set_m([1, 0, 0])
s.relax(save=[("fields", at("time", 0 * ps) | at("convergence"))])
s.save_restart_file(m0_filename)
del s
def set_to_zero(sim):
def H_ext(r):
return [0.0, 0.0, 0.0]
sim.set_H_ext(H_ext, unit=disturb_amplitude)
c = float(nm / SI("m"))
def set_disturbance(sim):
from nmag import SI, every, at
mat_Py = nmag.MagMaterial(name="Py",
Ms=SI(0.86e6, "A/m"),
exchange_coupling=SI(13.0e-12, "J/m"),
llg_damping=SI(0.5, ""))
sim = nmag.Simulation()
sim.load_mesh("bar30_30_100.nmesh.h5", [("Py", mat_Py)],
unit_length=SI(1e-9, "m"))
sim.set_m([1, 0, 1])
#Need to call advance time to create timestepper
ps = SI(1e-12, "s")
sim.advance_time(0 * ps)
sim.get_timestepper().set_params(rel_tolerance=1e-6, abs_tolerance=1e-6)
starttime = time.time()
sim.relax(save=[('averages',
every('time', 5 * ps)), ('fields', at('convergence'))])
stoptime = time.time()
print "Time spent is %5.2f seconds" % (stoptime - starttime)
ksp_tols = {
"DBC.rtol": 1e-7,
"DBC.atol": 1e-7,
"DBC.maxits": 1000000,
"NBC.rtol": 1e-7,
"NBC.atol": 1e-7,
"NBC.maxits": 1000000,
"PC.rtol": 1e-3,
"PC.atol": 1e-6,
"PC.maxits": 1000000
}
# Create the simulation object
sim = nmag.Simulation(ksp_tolerances=ksp_tols)
# Load the mesh
sim.load_mesh(mesh_name, [("Permalloy", Py)], unit_length=SI(1e-9, "m"))
# Load the initial magnetisation
sim.load_m_from_h5file(relax_name + ".h5")
# Set the applied magnetic field
sim.set_H_ext(H_direction_normalized, SI(H, 'A/m'))
# Set convergence parameters
sim.set_params(stopping_dm_dt=0.0, ts_abs_tol=1e-7, ts_rel_tol=1e-7)
# Save the information ever 5ps, and exit after 20ns.
sim.relax(save=[('fields', every('time', SI(dt, "s")))],
do=[('exit', at('time', SI(T, "s")))])
sim.load_mesh("bar30_30_100.nmesh.h5",
[("Py", mat_Py)],
unit_length=SI(1e-9,"m"))
sim.set_m([1,0,1])
#Need to call advance time to create timestepper
ps = SI(1e-12, "s")
sim.advance_time(0*ps)
sim.get_timestepper().set_params(rel_tolerance=1e-8,abs_tolerance=1e-8)
starttime = time.time()
sim.relax(save = [('averages', every('time', 5*ps)),
('fields', at('convergence'))])
stoptime = time.time()
print "Time spent is %5.2f seconds" % (stoptime-starttime)
# We model a bar 100 nm x 100 nm x 10 nm where a vortex sits in the center.
# This is part II: we load the vortex from file and apply a spin-polarised current
import nmag
from nmag import SI, every, at
# Define the material
mat_Py = nmag.MagMaterial(name="Py",
Ms=SI(0.8e6,"A/m"),
exchange_coupling=SI(13.0e-12, "J/m"),
llg_gamma_G=SI(0.2211e6, "m/A s"),
llg_polarisation=1.0,
llg_xi=0.05,
llg_damping=0.1)
# Define the simulation object and load the mesh
sim = nmag.Simulation()
sim.load_mesh("pyfilm.nmesh.h5", [("Py", mat_Py)], unit_length=SI(1e-9,"m"))
# Set the initial magnetisation: part II uses the one saved by part I
sim.load_m_from_h5file("vortex_m.h5")
sim.set_current_density([1e12, 0, 0], unit=SI("A/m^2"))
sim.set_params(stopping_dm_dt=0.0) # * WE * decide when the simulation should stop!
sim.relax(save=[('fields', at('convergence') | every('time', SI(1.0e-9, "s"))),
('averages', every('time', SI(0.05e-9, "s")) | at('stage_end'))],
do = [('exit', at('time', SI(10e-9, "s")))])
# ^^^ this is a technicality: functions have to return pure number.
# H_setter returns the field in units of gaussian_amplitude.
# We then compute H, the float components in such units.
def H_setter(r):
x, y, z = r
return ([H[0], H[1], H[2]+amplitude]
if x < 6.5e-9 else H)
# ^^^ apply the pulse only to the first dot
H_value = H_setter if abs(amplitude) > 1e-4 else H
# ^^^ to speed up things
fieldname = 'H_ext'
sim._fields.set_subfield(None, # subfieldname
H_value,
gaussian_amplitude,
fieldname=fieldname,
auto_normalise=False)
(mwe, field) = sim._master_mwes_and_fields_by_name[fieldname]
ocaml.lam_set_field(sim._lam, field, "v_" + fieldname)
print "*",
sim.pre_rhs_funs.append(update_H_ext)
sim.set_params(stopping_dm_dt=0) # Never stop for convergence
sim.relax(save=[#('averages', every('time', 2.5*ps)),
('fields', every('time', 20*ps))],
do=[('exit', at('stage_time', 5000*ps))])
# Set additional parameters for the time-integration and run the simulation
sim.set_params(stopping_dm_dt=stopping_dm_dt,
ts_rel_tol=1e-7, ts_abs_tol=1e-7)
sim.relax(save=save, do=do)
return sim
# If the initial magnetisation has not been calculated and saved into
# the file relaxed_m_file, then do it now!
if not os.path.exists(relaxed_m_file):
# Initial direction for the magnetisation
def m0(p):
x, y, z = p
tmp = min(1.0, max(-1.0, float(SI(x, "m")/(mesh_unit*hl))))
angle = 0.5*math.pi*tmp
return [math.sin(angle), math.cos(angle), 0.0]
save = [('fields', at('step', 0) | at('stage_end')),
('averages', every('time', SI(5e-12, 's')))]
sim = run_simulation(sim_name="relaxation", initial_m=m0,
damping=0.5, j=0.0, save=save,
stopping_dm_dt=1.0*degrees_per_ns)
sim.save_restart_file(relaxed_m_file)
del sim
# Now we simulate the magnetisation dynamics
save = [('averages', every('time', SI(9e-12, 's')))]
do = [('exit', at('time', SI(6e-9, 's')))]
run_simulation(sim_name="dynamics", initial_m=relaxed_m_file, damping=0.02,
j=0.1e12, P=1.0, save=save, do=do, stopping_dm_dt=0.0)
# We model a bar 100 nm x 100 nm x 10 nm where a vortex sits in the center.
# This is part I: we just do a relaxation to obtain the shape of the vortex.
import math, nmag
from nmag import SI, at
from nsim.si_units.si import degrees_per_ns
# Define the material
mat_Py = nmag.MagMaterial(name="Py",
Ms=SI(0.8e6,"A/m"),
exchange_coupling=SI(13.0e-12, "J/m"),
llg_gamma_G=SI(0.2211e6, "m/A s"),
llg_damping=1.0)
# Define the simulation object and load the mesh
sim = nmag.Simulation()
sim.load_mesh("pyfilm.nmesh.h5", [("Py", mat_Py)], unit_length=SI(1e-9,"m"))
# Set a initial magnetisation which will relax into a vortex
def initial_m(p):
x, y, z = p
return [-(y-50.0e-9), (x-50.0e-9), 40.0e-9]
sim.set_m(initial_m)
# Set convergence parameters and run the simulation
sim.set_params(stopping_dm_dt=1.0*degrees_per_ns)
sim.relax(save=[('fields', at('step', 0) | at('stage_end'))])
# Write the final magnetisation to file "vortex_m.h5"
sim.save_restart_file("vortex_m.h5")
#the computation of the demagnetising field
sim = nmag.Simulation(do_demag = False)
# define magnetic material so that Js = mu0*Ms = 1 T
Py = nmag.MagMaterial(name="Py",
Ms=1.0*si.Tesla/si.mu0,
exchange_coupling=SI(13.0e-12, "J/m"),
llg_damping = SI(0.0)
)
# load mesh
sim.load_mesh("sphere1.nmesh.h5",
[("sphere", Py)],
unit_length=SI(1e-9,"m")
)
# set initial magnetisation
sim.set_m([1,1,1])
# set external field
Hs = nmag.vector_set(direction=[0.,0.,1.],
norm_list=[1.0],
units=1e6*SI('A/m')
)
ps = SI(1e-12, "s") # ps corresponds to one picosecond
# let the magnetisation precess around the direction of the applied field
sim.hysteresis(Hs,
save=[('averages', every('time', 0.1*ps))],
do=[('exit', at('time', 300*ps))])
# Pinning at the borders
def pinning(p):
x = float(SI(p[0], "m")/(hl*unit_length))
if abs(x) >= 0.999:
return 0.0
else:
return 1.0
mat_Py = MagMaterial('Py',
Ms=SI(0.86e6, 'A/m'),
exchange_coupling=SI(13e-12, 'J/m'))
s = Simulation()
s.load_mesh(run.get_mesh_file_name(),
[('region1', mat_Py)],
unit_length=unit_length)
s.set_m(m0)
s.set_pinning(pinning)
s.relax(save=[('fields', at('time', SI(0, 's')) | at('convergence'))])
s.set_m(m1)
s.relax(save=[('fields', at('stage_time', SI(0, 's'))
| at('convergence'))])
import nmag
from nmag import SI, at
#create simulation object
sim = nmag.Simulation()
# define magnetic material
Py = nmag.MagMaterial(name="Py",
Ms=SI(795774, "A/m"),
exchange_coupling=SI(13.0e-12, "J/m"))
# load mesh: the mesh dimensions are scaled by 100nm
sim.load_mesh("../example_mfm/disk.nmesh.h5", [("disk", Py)],
unit_length=SI(1e-9, "m"))
# set initial magnetisation
sim.set_m([0., 0., 1.])
# loop over the applied fields Hs
sim.relax(save=[('averages', 'fields', 'restart', at('convergence'))])
T = 5e-9
# Define magnetic material: PermAlloy
Py = nmag.MagMaterial(name="Py",
Ms=SI(Ms, 'A/m'),
exchange_coupling=SI(A, "J/m"),
llg_gamma_G=SI(gamma, 'm/A s'),
llg_damping=alpha)
# Create the simulation object
sim = nmag.Simulation()
# Load the mesh
sim.load_mesh(mesh_name, [("Permalloy", Py)], unit_length=SI(1e-9, "m"))
# Set initial magnetization state in positive z direction
sim.set_m([0.0, 0.0, 1.0])
# And set the external field
sim.set_H_ext([x_direction, y_direction, z_direction], SI(H, 'A/m'))
# Set convergence parameters
sim.set_params(stopping_dm_dt=0)
# Save all the information out at the start and at the end
sim.relax(save=[('fields', at('stage_end'))],
do=[('exit', at('time', SI(T, "s")))])
# Finally, save the system state for the dynamic stage to run from
sim.save_restart_file(sim_output_name + '.h5')
Ms=SI(0.86e6, 'A/m'),
exchange_coupling=SI(13.0e-12, 'J/m'))
s = FDSimulation(do_demag=True)
s.set_params(stopping_dm_dt=20*degrees_per_ns)
nm = SI(1e-9, "m")
def rectangle(pos):
# if (pos[0] >=10e-9 and pos[0] <= 20e-9 and
# pos[1] >=10e-9 and pos[1] <= 20e-9):
return 'magnetic'
# else:
# return None
s.create_mesh([5, 5, 1], [5.0*nm, 5.0*nm, 3.0*nm], mat_Py,regions=rectangle)
s.set_m([1, 1, 1])
Hs = nmag.vector_set(direction=[1.0, 1.0, 1.0],
norm_list=[1.00, 0.95, [], 0.1, 0.09, [],
-0.1, -0.15, [], -1.00],
units=1e6*SI('A/m'))
s.hysteresis(Hs, save=[('field_m', at('time', SI(0, 's')) | at('convergence'))])
# Process the results
NCOL=os.path.join(os.path.dirname(os.path.abspath(nmag.__file__)), "../../bin/ncol")
os.system(NCOL + " run_fdsimulation H_ext_0 H_ext_1 H_ext_2 M_Py_0 M_Py_1 M_Py_2 > fd.dat")
os.system("gnuplot plot.gnp")
import nmag
from nmag import SI, every, at
mat_Py1 = nmag.MagMaterial(name="Py1",
Ms=SI(0.86e6, "A/m"),
exchange_coupling=SI(13.0e-12, "J/m"),
llg_damping=0.5)
mat_Py2 = nmag.MagMaterial(name="Py2",
Ms=SI(0.86e6, "A/m"),
exchange_coupling=SI(13.0e-12, "J/m"),
llg_damping=0.5)
#Example 1: both materials have same magnetisation
sim = nmag.Simulation()
sim.load_mesh("sphere_in_box.nmesh.h5", [("Py1", mat_Py1), ("Py2", mat_Py2)],
unit_length=SI(15e-9, "m"))
sim.set_m([1, 0, 0])
sim.relax(save=[('averages', 'fields', 'restart',
every('step', 1000) | at('convergence'))])
v = (1.0e-9, dz, -dy)
vn = (1.0e-9**2 + dy * dy + dz * dz)**0.5
return tuple(vi / vn for vi in v)
sim.set_m(m0)
sim.set_H_ext([0, 0, 0], SI("A/m"))
# Direction of the polarization
sim.model.quantities["sl_fix"].set_value(Value([0, 1, 0]))
# Current density
sim.model.quantities["sl_current_density"].set_value(Value(SI(0.1e12,
"A/m^2")))
if do_relaxation:
print "DOING RELAXATION"
sim.relax(save=[("fields", at("time", 0 * ps) | at("convergence"))])
sim.save_m_to_file(relaxed_m)
sys.exit(0)
else:
print "DOING DYNAMICS"
sim.load_m_from_h5file(relaxed_m)
sim.set_params(stopping_dm_dt=0 * degrees_per_ns)
sim.relax(save=[("averages", every("time", 5 * ps))],
do=[("exit", at("time", 10000 * ps))])
# ipython()
# The magnetisation is defined over all the three regions,
# but is pinned in region A and C.
offset = 2e-9 # m (meters)
length = 500e-9 # m
# Set initial magnetisation
def sample_m0((x, y, z)):
# relative_position goes linearly from -1 to +1 in region B
relative_position = -2*(x - offset)/length + 1
mz = min(1.0, max(-1.0, relative_position))
return [0, math.sqrt(1 - mz*mz), mz]
sim.set_m(sample_m0)
# Pin magnetisation outside region B
def sample_pinning((x, y, z)):
return x >= offset and x <= offset + length
sim.set_pinning(sample_pinning)
# Save the magnetisation along the x-axis
def save_magnetisation_along_x(sim):
f = open('bar_mag_x.dat', 'w')
for i in range(0, 504):
x = array([i+0.5, 0.5, 0.5]) * 1e-9
M = sim.probe_subfield_siv('M_Co', x)
print >>f, x[0], M[0], M[1], M[2]
# Relax the system
sim.relax(save=[(save_magnetisation_along_x, at('convergence'))])
import nmag
from nmag import SI, every, at
ocaml.init_hlib("/rhome/ak8w07/mumag/nmag/lib/libhmatrix-1.3.so")
# create simulation object
hp = {}
hp["nfdeg"] = 3
hp["nmin"] = 20
hp["p"] = 4
hp["eta"] = 2.0
hp["eps"] = 0.00001
sim = nmag.Simulation(name="bar_relax", use_hlib=True, use_pvode=False, hlib_params=hp)
mat_Py = nmag.MagMaterial(name="Py", Ms=SI(0.86e6, "A/m"), exchange_coupling=SI(13.0e-12, "J/m"), llg_damping=0.5)
sim.load_mesh("bar30_30_100.nmesh.h5", [("Py", mat_Py)], unit_length=SI(1e-9, "m"))
sim.set_m([1, 0, 1])
ps = SI(1e-12, "s")
sim.relax(save=[("averages", every("time", 5 * ps)), ("fields", at("convergence"))])
origin=(pb.sx*0.5, pb.sy*0.5, pb.sz*0.5))
s.set_m(pb.m0)
Hs = nmag.vector_set(direction=rotate([0.0, 1.0, 0.0], pb.angle),
norm_list=[0.0, 0.0015, 0.003, 0.004,
0.0045, 0.0001, 0.0065],
units=1e6*SI('A/m'))
reference_mz = []
def check_switching_field(s):
m = s.get_subfield_average('m')
mz = abs(m[2])
if len(reference_mz) == 0:
reference_mz.append(mz)
else:
(mz0, ) = reference_mz
if mz < 0.05*mz0:
f = open("switching_fields.dat", "a")
H = [float(Hi/SI('A/m')) for Hi in Hs[s.stage-1]]
f.write("%g %g %g %g\n" % tuple([pb.angle] + H))
s.hysteresis_exit()
f.close()
print "check_switching_field: done!"
s.hysteresis(Hs,
save=[('field_m', at('convergence'))],
do=[(check_switching_field, at('convergence'))])
# We model a bar 100 nm x 100 nm x 10 nm where a vortex sits in the center.
# This is part II: we load the vortex from file and apply a spin-polarised current
import nmag
from nmag import SI, every, at
# Define the material
mat_Py = nmag.MagMaterial(name="Py",
Ms=SI(0.8e6, "A/m"),
exchange_coupling=SI(13.0e-12, "J/m"),
llg_gamma_G=SI(0.2211e6, "m/A s"),
llg_polarisation=1.0,
llg_xi=0.05,
llg_damping=0.1)
# Define the simulation object and load the mesh
sim = nmag.Simulation()
sim.load_mesh("pyfilm.nmesh.h5", [("Py", mat_Py)], unit_length=SI(1e-9, "m"))
# Set the initial magnetisation: part II uses the one saved by part I
sim.load_m_from_h5file("vortex_m.h5")
sim.set_current_density([1e12, 0, 0], unit=SI("A/m^2"))
sim.set_params(
stopping_dm_dt=0.0) # * WE * decide when the simulation should stop!
sim.relax(save=[('fields', at('convergence') | every('time', SI(1.0e-9, "s"))),
('averages', every('time', SI(0.05e-9, "s")) | at('stage_end'))
],
do=[('exit', at('time', SI(10e-9, "s")))])
# Set Demag tolerances.
ksp_tols = {"DBC.rtol": 1e-7,
"DBC.atol": 1e-7,
"DBC.maxits": 1000000,
"NBC.rtol": 1e-7,
"NBC.atol": 1e-7,
"NBC.maxits": 1000000,
"PC.rtol": 1e-3,
"PC.atol": 1e-6,
"PC.maxits": 1000000}
# Create the simulation object
sim = nmag.Simulation(ksp_tolerances=ksp_tols)
# Load the mesh
sim.load_mesh(mesh_name, [("Permalloy", Py)], unit_length=SI(1e-9, "m"))
# Load the initial magnetisation
sim.load_m_from_h5file(relax_name + ".h5")
# Set the applied magnetic field
sim.set_H_ext(H_direction_normalized, SI(H, 'A/m'))
# Set convergence parameters
sim.set_params(stopping_dm_dt=0.0, ts_abs_tol=1e-7, ts_rel_tol=1e-7)
# Save the information ever 5ps, and exit after 20ns.
sim.relax(save=[('fields', every('time', SI(dt, "s")))],
do=[('exit', at('time', SI(T, "s")))])
import nmag
from nmag import SI, si, at
# create simulation object
ps = SI(1e-12, "s")
sim = nmag.Simulation()
# define magnetic material (data from Kronmueller's book)
NdFeB = nmag.MagMaterial(
name="NdFeB",
Ms=1.6 * si.Tesla / si.mu0,
exchange_coupling=SI(7.3e-12, "J/m"),
anisotropy=nmag.uniaxial_anisotropy(axis=[0.01, 0.01, 1], K1=SI(4.3e6, "J/m^3"), K2=SI(0 * 0.65e6, "J/m^3")),
)
sim.load_mesh("cube.nmesh.h5", [("cube", NdFeB)], unit_length=SI(1.0e-9, "m"))
sim.set_m([-0.01, -0.01, 1])
Hs = nmag.vector_set(
direction=[0.0, 0.0, 1.0], norm_list=[-1, -2, [], -4, -4.2, [], -4.9, -4.91, [], -4.94], units=1e6 * SI("A/m")
)
sim.hysteresis(Hs, save=[("fields", "restart", at("convergence"))])
sim.load_mesh('%s' % mesh_file, [('Mat_Hard', Mat_Hard),
('Mat_Soft', Mat_Soft)],
unit_length=SI(1e-9, 'm'))
sim.set_m([0, 0, 1])
Hs = nmag.vector_set(direction=[0, 0, 1],
norm_list=[0.0, -0.01, [], -1.0],
units=H_max * SI('A/m'))
def my_save(sim):
# only save M, m, H_ext
sim.save_data(fields=['M', 'm', 'H_ext'])
def print_time(sim):
sim_time = float(sim.time / SI(1e-12, 's'))
print('----SIM Time %f ps----' % sim_time)
# start time
start_time = time.time()
sim.hysteresis(Hs,
save=[(my_save, at('convergence'))],
do=[(print_time,
every('time', SI(50e-12, 's')) | at('convergence'))])
use_time = (time.time() - start_time) / 60
print('Use Time %f min' % use_time)
import nmag
from nmag import SI, every, at, si
#create simulation object and switch off
#the computation of the demagnetising field
sim = nmag.Simulation(do_demag=False)
# define magnetic material so that Js = mu0*Ms = 1 T
Py = nmag.MagMaterial(name="Py",
Ms=1.0 * si.Tesla / si.mu0,
exchange_coupling=SI(13.0e-12, "J/m"),
llg_damping=SI(0.0))
# load mesh
sim.load_mesh("sphere1.nmesh.h5", [("sphere", Py)], unit_length=SI(1e-9, "m"))
# set initial magnetisation
sim.set_m([1, 1, 1])
# set external field
Hs = nmag.vector_set(direction=[0., 0., 1.],
norm_list=[1.0],
units=1e6 * SI('A/m'))
ps = SI(1e-12, "s") # ps corresponds to one picosecond
# let the magnetisation precess around the direction of the applied field
sim.hysteresis(Hs,
save=[('averages', every('time', 0.1 * ps))],
do=[('exit', at('time', 300 * ps))])
Py = nmag.MagMaterial( name="Py",
Ms=SI(795774,"A/m"),
exchange_coupling=SI(13.0e-12, "J/m")
)
# load mesh: the mesh dimensions are scaled by 100nm
sim.load_mesh( "nanodot1.nmesh.h5",
[("cylinder", Py)],
unit_length=SI(100e-9,"m")
)
# set initial magnetisation
sim.set_m([1.,0.,0.])
Hs = nmag.vector_set( direction=[1.,0.,0.],
norm_list=[1000.0, 900.0, [],
95.0, 90.0, [],
-100.0, -200.0, [],
-1000.0, -900.0, [],
-95.0, -90.0, [],
100.0, 200.0, [], 1000.0],
units=1e3*SI('A/m')
)
# loop over the applied fields Hs
sim.hysteresis(Hs,
save=[('averages', 'fields', 'restart', at('convergence'))]
)
y_lattice = 10.01 # between repeated copies of the simualtion cell
z_lattice = 0.0
# list to store the lattice points where the periodic
# copies of the simulation cell will be placed
lattice_points = []
for xi in range(-4, 6):
for yi in range(-19, 21):
lattice_points.append(
[xi * x_lattice, yi * y_lattice, 0.0 * z_lattice])
# create data structure pbc for this macro geometry
pbc = nmag.SetLatticePoints(vectorlist=lattice_points,
scalefactor=SI(1e-9, 'm'))
#create simulation object, passing macro geometry data structure
sim = nmag.Simulation(periodic_bc=pbc.structure)
# load mesh
sim.load_mesh("prism.nmesh.h5", [("repeated-prism-2D", Py)],
unit_length=SI(1e-9, "m"))
# set initial magnetisation
sim.set_m([1., 1., 1.])
# loop over the applied field
s = SI(1, "s")
sim.relax(save=[('averages', 'fields',
every('time', 5e-12 * s) | at('convergence'))])
import nmag
from nmag import SI, at
#create simulation object
sim = nmag.Simulation()
# define magnetic material
Py = nmag.MagMaterial(name="Py",
Ms=SI(1e6, "A/m"),
exchange_coupling=SI(13.0e-12, "J/m"))
# load mesh: the mesh dimensions are scaled by 0.5 nm
sim.load_mesh("ellipsoid.nmesh.h5", [("ellipsoid", Py)],
unit_length=SI(1e-9, "m"))
# set initial magnetisation
sim.set_m([1., 1., 0.])
Hs = nmag.vector_set(direction=[1., 1., 0.],
norm_list=[1.0, 0.995, [], -1.0, -0.995, -0.990, [], 1.0],
units=1e6 * SI('A/m'))
# loop over the applied fields Hs
sim.hysteresis(Hs, save=[('averages', at('convergence'))])
s.load_mesh(mesh_filename, [('bar', permalloy)], unit_length=1*nm)
def set_disturbance(is_on):
c = float(nm/SI('m'))
def setter(sim):
def H_ext(r):
x, y, z = [xi/c - x0i
for xi, x0i in zip(r, disturb_origin)]
# x, y and z are (floats) in nanometers
d = math.sqrt(x*x + y*y + z*z)
if is_on and d < disturb_radius:
return disturb_direction
else:
return [0.0, 0.0, 0.0]
sim.set_H_ext(H_ext, unit=disturb_amplitude)
return setter
if not relaxed:
s.set_m([1, 0, 0])
s.relax()
s.save_restart_file(m0_filename)
else:
s.load_m_from_h5file(m0_filename)
s.relax(save=[('field_m', every('time', 0.5*ps))],
do=[(set_disturbance(True), at('time', 0*ps)),
(set_disturbance(False), at('time', disturb_duration)),
('exit', at('time', 1000*ps))])
H_direction_normalized = list(H_direction / np.linalg.norm(H_direction))
# Total simulation time
T = 5e-9
# Define magnetic material: PermAlloy
Py = nmag.MagMaterial(
name="Py", Ms=SI(Ms, "A/m"), exchange_coupling=SI(A, "J/m"), llg_gamma_G=SI(gamma, "m/A s"), llg_damping=alpha
)
# Create the simulation object
sim = nmag.Simulation()
# Load the mesh
sim.load_mesh(mesh_name, [("Permalloy", Py)], unit_length=SI(1e-9, "m"))
# Set initial magnetization state in positive z direction
sim.set_m([0.0, 0.0, 1.0])
# And set the external field
sim.set_H_ext(H_direction_normalized, SI(H, "A/m"))
# Set convergence parameters
sim.set_params(stopping_dm_dt=0)
# Save all the information out at the start and at the end
sim.relax(save=[("fields", at("stage_end"))], do=[("exit", at("time", SI(T, "s")))])
# Finally, save the system state for the dynamic stage to run from
sim.save_restart_file(sim_output_name + ".h5")
sim = nmag.Simulation()
# define magnetic material Cobalt (data from OOMMF materials file)
Co = nmag.MagMaterial(name="Co",
Ms=SI(1400e3, "A/m"),
exchange_coupling=SI(30e-12, "J/m"),
anisotropy=nmag.uniaxial_anisotropy(axis=[0, 0, 1],
K1=SI(
520e3, "J/m^3")))
# define magnetic material Permalley
Py = nmag.MagMaterial(name="Py",
Ms=SI(860e3, "A/m"),
exchange_coupling=SI(13.0e-12, "J/m"))
# load mesh
sim.load_mesh("two_cubes.nmesh.h5", [("cube1", Py), ("cube2", Co)],
unit_length=SI(1e-9, "m"))
# set initial magnetisation along the
# positive x axis for both cubes, slightly off in z-direction
sim.set_m([0.999847695156, 0, 0.01745240643731])
ns = SI(1e-9, "s") # corresponds to one nanosecond
sim.relax(
save=[('averages',
every('time', 0.01 *
ns)), ('fields',
every('time', 0.05 * ns) | at('convergence'))])
H_pulse_data = sim.get_subfield("H_ext")
# Do the same for the bias field
sim.set_H_ext(bias_H)
H_bias_data = sim.get_subfield("H_ext")
# Now the applied field at time t will be expressed as
# H_bias_data + f(t)*H_pulse_data,
# where f(t) is the time dependence of the pulse
def update_H_ext(t_su):
ut = float(sinc_omega*(t_su*ps - sinc_t0*ps))
t_amp = math.sin(ut)/ut if abs(ut) > 1e-10 else 1.0
if abs(t_amp) > 1e-4:
H_value = H_bias_data + t_amp*H_pulse_data
else:
H_value = map(lambda x: float(x/SI("A/m")), bias_H)
fieldname = 'H_ext'
sim._fields.set_subfield(None, H_value, SI("A/m"),
fieldname=fieldname, auto_normalise=False)
(mwe, field) = sim._master_mwes_and_fields_by_name[fieldname]
ocaml.lam_set_field(sim._lam, field, "v_" + fieldname)
print "*",
sim.pre_rhs_funs.append(update_H_ext)
sim.set_params(stopping_dm_dt=0) # Never stop for convergence
sim.relax(save=[('fields', every('time', 10*ps))],
do=[('exit', at('stage_time', 10240*ps))])
H_max = 17 * 1e3 * 1e3 / (4 * math.pi) # koe to A/m
Hs = nmag.vector_set(direction=[0, 0, 1],
norm_list=[-1.0, 1.0],
units=H_max * SI('A/m'))
def my_save(sim):
# only save M, m, H_ext
sim.save_data(fields=['M', 'm', 'H_ext'])
def print_time(sim):
sim_time = float(sim.time / SI(1e-12, 's'))
print('----SIM Time %f ps----' % sim_time)
# start time
start_time = time.time()
sim.set_H_ext([0, 0, -H_max], SI('A/m'))
sim.relax(save=[(my_save, at('convergence'))],
do=[(print_time, every('time', SI(50e-12, 's')) | at('convergence'))
])
sim.set_H_ext([0, 0, H_max], SI('A/m'))
sim.relax(save=[(my_save, at('convergence'))],
do=[(print_time, every('time', SI(50e-12, 's')) | at('convergence'))
])
use_time = (time.time() - start_time) / 60
print('Use Time %f min' % use_time)
sim.load_mesh("bar30_30_100.nmesh.h5",
[("Py", mat_Py)],
unit_length=SI(1e-9,"m"))
sim.set_m([1,0,1])
#Need to call advance time to create timestepper
ps = SI(1e-12, "s")
sim.advance_time(0*ps)
sim.get_timestepper().set_params(rel_tolerance=1e-6,abs_tolerance=1e-6)
starttime = time.time()
sim.relax(save = [('averages', every('time', 5*ps)),
('fields', at('convergence'))])
stoptime = time.time()
print "Time spent is %5.2f seconds" % (stoptime-starttime)
# Set initial magnetisation
def sample_m0((x, y, z)):
# relative_position goes linearly from -1 to +1 in region B
relative_position = -2 * (x - offset) / length + 1
mz = min(1.0, max(-1.0, relative_position))
return [0, math.sqrt(1 - mz * mz), mz]
sim.set_m(sample_m0)
# Pin magnetisation outside region B
def sample_pinning((x, y, z)):
return x >= offset and x <= offset + length
sim.set_pinning(sample_pinning)
# Save the magnetisation along the x-axis
def save_magnetisation_along_x(sim):
f = open('bar_mag_x.dat', 'w')
for i in range(0, 504):
x = array([i + 0.5, 0.5, 0.5]) * 1e-9
M = sim.probe_subfield_siv('M_Co', x)
print >> f, x[0], M[0], M[1], M[2]
# Relax the system
sim.relax(save=[(save_magnetisation_along_x, at('convergence'))])