def run_simulation(simname, meshfile, hmatrix=None, tol=0.000001):
T_start = time.time()
sim = nmag.Simulation(name=simname, phi_BEM=hmatrix)
Ni = nmag.MagMaterial(name="Ni",
Ms=SI(493380, "A/m"),
exchange_coupling=SI(7.2e-12, "J/m"),
llg_damping=1.0)
ps = SI(1e-12, "s")
sim.load_mesh(meshfile, [("thinfilm", Ni)], unit_length=SI(1e-9, "m"))
sim.set_m([0.05, 0.02, 1.00])
sim.set_params(ts_abs_tol=tol, ts_rel_tol=tol)
sim.set_H_ext([0, 0, 0], SI('A/m'))
dt = SI(5e-12, "s")
T_end = time.time()
T_setup = T_end - T_start
T_start = time.time()
sim.relax(save=[('averages', every('time', 10 * ps))])
T_end = time.time()
T_sim = T_end - T_start
sim.save_data(['m'])
number_nodes = len(sim.mesh.points)
mem_rss = get_memory_of_process() / 1024.0
return [number_nodes, mem_rss, T_setup, T_sim]
def run_simulation(simname,meshfile,hmatrix=None,tol=0.000001):
T_start = time.time()
sim = nmag.Simulation(name=simname,phi_BEM=hmatrix)
Ni = nmag.MagMaterial(name="Ni",
Ms=SI(493380, "A/m"),
exchange_coupling=SI(7.2e-12, "J/m"),
llg_damping=1.0)
ps = SI(1e-12,"s")
sim.load_mesh(meshfile, [("thinfilm", Ni)], unit_length=SI(1e-9, "m"))
sim.set_m([0.05,0.02,1.00])
sim.set_params(ts_abs_tol=tol,ts_rel_tol=tol)
sim.set_H_ext([0,0,0], SI('A/m'))
dt = SI(5e-12, "s")
T_end = time.time()
T_setup = T_end - T_start
T_start = time.time()
sim.relax(save=[('averages',every('time', 10*ps))])
T_end = time.time()
T_sim = T_end - T_start
sim.save_data(['m'])
number_nodes = len(sim.mesh.points)
mem_rss = get_memory_of_process() / 1024.0
return [number_nodes,mem_rss,T_setup,T_sim]
def simulation(
sim_name=None, initial_m=None, Hs=[None], save=[], do=[], have_j=False, damping_Py=0.01, damping_FePt=0.1
):
if have_j:
have_j = 1.0
else:
have_j = 0.0
# FeNi, Permalloy
mat_Py = nmag.MagMaterial(
name="Py",
Ms=SI(0.86e6, "A/m"),
exchange_coupling=SI(13.0e-12, "J/m"),
llg_damping=damping_Py,
llg_polarisation=have_j * SI(1.0),
llg_xi=SI(0.01),
)
anis_FePt = nmag.uniaxial_anisotropy(axis=[1, 0, 0], K1=SI(2.5e6, "J/m^3"))
mat_FePt = nmag.MagMaterial(
name="FePt",
Ms=SI(1e6, "A/m"),
exchange_coupling=SI(10.0e-12, "J/m"),
anisotropy=anis_FePt,
llg_damping=damping_FePt,
llg_polarisation=have_j * SI(1.0),
llg_xi=SI(0.01),
)
s = nmag.Simulation(sim_name)
s.set_local_magnetic_coupling(mat_Py, mat_FePt, SI(2.0e-4, "N/A^2"))
s.load_mesh(
mesh_filename,
[
("HARD-LEFT", mat_FePt),
("SOFT-LEFT", mat_Py),
("HARD-CENTER", mat_FePt),
("SOFT-RIGHT", mat_Py),
("HARD-RIGHT", mat_FePt),
],
unit_length=SI(1e-9, "m"),
)
if type(initial_m) == str: # Set the initial magnetisation
s.load_m_from_h5file(initial_m) # a) from file if a string is provided
else:
s.set_m(initial_m[0], "m_Py")
s.set_m(initial_m[1], "m_FePt")
s.hysteresis(Hs, save=save, do=do, convergence_check=every(5, "step"))
return s
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))])
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))])
# Obtain the initial magnetisation configuration (S-state) if necessary
m0_file = "m0.h5"
if "relax" in sys.argv:
s = new_simulation('relaxation', alpha=1.0)
Hs = nmag.vector_set(direction=[1, 1, 1],
norm_list=[1.00, 0.95, [], 0.0],
units=2e6*SI("A/m"))
s.set_m([1, 1, 1])
s.hysteresis(Hs)
s.save_restart_file(m0_file)
del s
# Run the dynamic simulation for field 1
if "field1" in sys.argv:
s = new_simulation('field1')
s.load_m_from_h5file(m0_file)
s.set_H_ext([-24.6, 4.3, 0.0], mT/mu0)
s.relax(save=[('averages', every('time', SI(10e-12, "s"))),
('fields', at('convergence'))])
# Run the dynamic simulation for field 2
if "field2" in sys.argv:
s = new_simulation('field2')
s.load_m_from_h5file(m0_file)
s.set_H_ext([-35.5, -6.3, 0.0], mT/mu0)
s.relax(save=[('averages', every('time', SI(10e-12, "s"))),
('fields', at('convergence'))])
def do_simulation():
import time
import nmag
#import nsim.logtools
#import logging
#
#nsim.logtools.setGlobalLogLevel(logging.DEBUG)
from nmag import SI, mesh
import os
mat1 = nmag.MagMaterial(name="mat1",
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=0.5)
mat2 = nmag.MagMaterial(name="mat2",
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=0.5)
sim1 = nmag.Simulation(name="simulation1")
sim1.load_mesh("bar.nmesh.h5",
[("one", mat1), ("two", mat2)],
unit_length=SI(1e-9,"m"))
sim2 = nmag.Simulation(name="simulation2")
sim2.load_mesh("bar.nmesh.h5",
[("one", mat1), ("two", mat1)],
unit_length=SI(1e-9,"m"))
import math
angle_deg = 45
angle_rad = angle_deg/360.*2*math.pi
sim2.set_m([math.cos(angle_rad), 0, math.sin(angle_rad)])
sim2.set_params(ts_rel_tol=2.7e-05 , ts_abs_tol=2.7e-05)
def norm(p):
return math.sqrt(p[0]**2 + p[1]**2 + p[2]**2)
def dist(p1, p2):
return math.sqrt((p1[0]-p2[0])**2 + (p1[1]-p2[1])**2 + (p1[2]-p2[2])**2)
# First we check consistency between the meshes
ps1 = sim1.mesh.points
ps2 = sim2.mesh.points
if len(ps1) != len(ps2): raise "Mesh size inconsistency!"
for i in range(len(ps1)):
p1, p2 = (ps1[i], ps2[i])
d = dist(p1, p2)
if d > 1e-12:
raise "Mesh coords inconsistency!"
def build_key(p):
return ",".join(["%8f" % round(pi, 6) for pi in p])
# Now we can assume that the indexing is the same
i = 0
pcs = {}
for p in ps1:
pcs[build_key(p)] = i
i += 1
max_ds = []
max_drels = []
def consistency_check(_):
m2 = sim2.get_subfield("m_mat1")
def m(p):
return m2[pcs[build_key([pi*1e9 for pi in p])]]
sim1.set_m(m, "m_mat1")
sim1.set_m(m, "m_mat2")
Hd1 = sim1.get_subfield("H_demag")
Hd2 = sim2.get_subfield("H_demag")
if len(Hd1) != len(Hd2):
raise "Demag field size mismatch!"
n = len(Hd1)
max_d = None
max_drel = None
for i in range(n):
d = dist(Hd1[i], Hd2[i])
if max_d == None or d > max_d:
max_d = d
max_drel = d/(norm(Hd1[i]) + norm(Hd2[i]))
max_ds.append(max_d)
max_drels.append(max_drel)
msg = "Deviation in the demag fields: " \
"absolute %s, percentual %s" % (max_d, max_drel)
out(msg)
from nmag import every
sim2.relax(do=[(consistency_check, every("time", SI(50e-12, "s")))], save=[])
assert max(max_drels) < 0.0011, "Test failed: demag differs by more than 0.1 %"
assert max(max_ds) < 1000.0, "Test failed: demag differs by more than 1000 A/m"
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'))])
# 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")))])
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)
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))])
# 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 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)
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")))])
# example 2 of the nmag documentation
# without demag but with external field
mat_Py = nmag.MagMaterial(name="Py",
Ms=SI(0.86e6, "A/m"),
exchange_coupling=SI(13.0e-12, "J/m"),
llg_damping=0.1)
L = 30.0e-9
H = 10.0e-9
W = 10.0e-9
def m0(r):
mx = 2 * r[0] / L - 1
my = 2 * r[1] / W - 1
mz = 1
return [mx, my, mz]
sim = nmag.Simulation("bar", do_demag=False)
sim.load_mesh("bar.nmesh.h5", [("Py", mat_Py)], unit_length=SI(1e-9, "m"))
sim.set_H_ext([1, 0, 0], SI(0.43e6, "A/m"))
sim.set_m(m0)
sim.set_params(stopping_dm_dt=1 * degrees_per_ns,
ts_rel_tol=1e-6,
ts_abs_tol=1e-6)
sim.relax(save=[('averages', every('time', SI(5e-11, "s")))])
sim.set_H_ext(H_ext, unit=disturb_amplitude)
c = float(nm / SI("m"))
def set_disturbance(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 x < disturb_thickness:
return disturb_direction
else:
return [0.0, 0.0, 0.0]
sim.set_H_ext(H_ext, unit=disturb_amplitude)
s = simulate_nanowire("dynamics", 0.05)
s.load_m_from_h5file(m0_filename)
s.relax(
save=[("fields", every("time", 0.5 * ps))],
do=[
(set_disturbance, at("time", 0 * ps)),
(set_to_zero, at("time", disturb_duration)),
("exit", at("time", 5000 * ps)),
],
)
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'))])
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'))])
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",
#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))])
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'))])
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, 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, 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"))])
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()
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, 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))])
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)
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)
# ^^^ 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))])
# 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")))])
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)
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))])
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, every
# This basic simulation gives us an idea about the relaxation properties
# of the system.
# We find that it takes about 200 frames to do one full oscillation,
# which corresponds to a frequency of about f=1 GHz.
#create simulation object
sim = nmag.Simulation()
# define magnetic material
Py = nmag.MagMaterial(name='Py',
Ms=SI(1e6, 'A/m'),
llg_damping=0.02,
exchange_coupling=SI(13.0e-12, 'J/m'))
# load mesh
sim.load_mesh('rod.nmesh.h5', [('rod', Py)], unit_length=SI(1e-9, 'm'))
# set initial magnetisation
sim.set_m([1, 0, 0.1])
# set external field
sim.set_H_ext([0, 0, 0], SI('A/m'))
sim.relax(save=[('fields', every('time', SI(5e-12, "s")))])
# 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))
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=[#('averages', every('time', 2.5*ps)),
('field_m', every('time', 1*ps))],
do=[('exit', at('stage_time', 5000*ps))])
import nmag
from nmag import SI, every
# This basic simulation gives us an idea about the relaxation properties
# of the system.
# We find that it takes about 200 frames to do one full oscillation,
# which corresponds to a frequency of about f=1 GHz.
#create simulation object
sim = nmag.Simulation()
# define magnetic material
Py = nmag.MagMaterial(name = 'Py',
Ms = SI(1e6, 'A/m'),
llg_damping=0.02,
exchange_coupling = SI(13.0e-12, 'J/m'))
# load mesh
sim.load_mesh('rod.nmesh.h5',
[('rod', Py)],
unit_length = SI(1e-9, 'm'))
# set initial magnetisation
sim.set_m([1,0,0.1])
# set external field
sim.set_H_ext([0,0,0], SI('A/m'))
sim.relax(save =[('fields', every('time', SI(5e-12,"s")))])
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))])
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)
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")
