def excite_system_K(mesh, Hx=2000):
A = 1.3e-11
Ms = 8.6e5
mu0 = 4 * np.pi * 1e-7
G = A / (mu0 * Ms**2)
Nx = 0
Ny = 0.4
Nz = 0.6
K = 0.5 * (Ny - Nx) * mu0 * Ms**2
Kp = -0.5 * (Nz - Ny) * mu0 * Ms**2
sim = Sim(mesh, name='dyn_K')
sim.set_tols(rtol=1e-8, atol=1e-8)
sim.gamma = 2.211e5
sim.Ms = Ms
sim.alpha = 0.005
sim.set_m(np.load('m0.npy'))
exch = UniformExchange(A=A)
sim.add(exch)
kx = UniaxialAnisotropy(K, axis=(1, 0, 0))
sim.add(kx)
kp = UniaxialAnisotropy(Kp, axis=(0, 0, 1))
sim.add(kp)
hx = Zeeman((Hx, 0, 0), name='Hx')
sim.add(hx, save_field=True)
ts = np.linspace(0, 5e-9, 501)
for t in ts:
print 'time', t
sim.run_until(t)
def relax_system(mesh):
A = 1.3e-11
Ms = 8.6e5
mu0 = 4 * np.pi * 1e-7
Nx = 0
Ny = 0.4
Nz = 0.6
K = 0.5 * (Ny - Nx) * mu0 * Ms**2
Kp = -0.5 * (Nz - Ny) * mu0 * Ms**2
sim = Sim(mesh, name='relax')
sim.set_tols(rtol=1e-8, atol=1e-8)
sim.gamma = 2.211e5
sim.Ms = Ms
sim.alpha = 0.5
sim.do_procession = False
sim.set_m(init_dw)
exch = UniformExchange(A=A)
sim.add(exch)
kx = UniaxialAnisotropy(K, axis=(1, 0, 0))
sim.add(kx)
kp = UniaxialAnisotropy(Kp, axis=(0, 0, 1))
sim.add(kp)
sim.relax(dt=1e-14,
stopping_dmdt=0.01,
max_steps=5000,
save_m_steps=None,
save_vtk_steps=None)
np.save('m0.npy', sim.spin)