theta = 40.0; phi = 90.0 # Polarization direction
length, width, thick = (12.5*nm, 12.5*nm, 5*nm) # System geometry
I = SI(5e-5, "A"); current_density = I/(length*width) # Applied current
Happ_dir = [0.2, 0.2, 10.0] # Applied field (mT)
# Create the mesh, if it does not exist
mesh_filename = "film.nmesh.h5"
if not os.path.exists(mesh_filename):
mesh_geo = \
("algebraic3d\n"
"solid cube = orthobrick (0, 0, 0; %s, %s, %s) -maxh = 2.5;\n"
"tlo cube;\n" % tuple(map(lambda x: float(x/nm), (length, width, thick))))
netgen_mesh_from_string(mesh_geo, mesh_filename, keep_geo=True)
# Material definition
anis = uniaxial_anisotropy(axis=[0, 0, 1], K1=-SI(0.1e6, "J/m^3"))
mat = MagMaterial("Py",
Ms=SI(860e3, "A/m"),
exchange_coupling=SI(13e-12, "J/m"),
llg_gamma_G=SI(221017, "m/s A"),
llg_damping=SI(0.014),
anisotropy=anis)
mat.sl_P = 0.4 # Polarisation
mat.sl_lambda = 2.0 # lambda parameter
mat.sl_d = SI(5.0e-9, "m") # Free layer thickness
sim = Simulation(do_sl_stt=True, do_demag=False)
sim.load_mesh(mesh_filename, [("region1", mat)], unit_length=nm)
sim.set_m([1, 0.01, 0.01])
sim.set_H_ext(Happ_dir, 0.001*Tesla/mu0)
# One dimensional magnetic system studied using nsim
import math
from nmag import vector_set, SI
import nmag.nmag5 as nmag
from nsim.si_units.si import mu0, Tesla, degrees_per_ns
#--------------------------------------------
#--- Details about the layers and the mesh and the material
# Choose Co as a material
anisotropy = \
nmag.uniaxial_anisotropy(axis=[(1.0/3)**0.5, (1.0/3)**0.5, (1.0/3)**0.5],
K1=SI(0.7e6, "J/m^3"),
K2=SI(0.18e6, "J/m^3"))
anisotropy.declare("SpaceField", "K1")
mat_Co = nmag.MagMaterial(
name="Co",
Ms=SI(1.42444e6, "A/m"),
exchange_coupling=SI(3.02e-11, "J/m"),
anisotropy=anisotropy,
llg_gamma_G=SI(0.2211e6, "m/ A s"),
llg_normalisationfactor=SI(0.001e12, "1/s"))
mesh_name = "uniaxial_1d"
mesh_unit = SI(1e-9, "m")
new_mesh = True
#--------------------------------------------
## The initial configuration and how the applied field should change
import os, sys, math
from nmag.constants import degrees_per_ns, mu0
from nmag.common import * # import every, at, etc.
# New Nmag5 imports: import nmag5 under the name "nmag"
from nmag.nmag5 import MagMaterial, Simulation, uniaxial_anisotropy, SI
from nsim.model import Value
anisotropy = \
uniaxial_anisotropy(axis=[0, 0, 1], K1=SI(0.0, "J/m^3"))
mag = \
MagMaterial(name="a",
Ms=SI(0.5e6, "A/m"),
exchange_coupling=SI(13e-12, "J/m"),
anisotropy=anisotropy,
llg_damping=0.5,
llg_gamma_G=SI(0.2211e6, "m/A s"))
# Create the simulation object
sim = Simulation()
# We want some constants to be spatially dependent
sim.declare("spacefield", "alpha", "Ms", "gamma_G", "exchange_factor")
anisotropy.declare("spacefield", "K1")
# Load the mesh
mats = [("bottom", mag), ("top", mag)]
sim.load_mesh("spatially.nmesh.h5", mats, unit_length=SI(1e-9, "m"))
