def excite_system(mesh):
sim = Sim(mesh, name='dyn', driver='sllg')
sim.set_options(dt=1e-14, gamma=const.gamma, k_B=const.k_B)
sim.driver.alpha = 0.1
sim.mu_s = const.mu_s_1
sim.T = temperature_gradient
sim.set_m(np.load("m0.npy"))
J = 50.0 * const.k_B
exch = UniformExchange(J)
sim.add(exch)
D = 0.5 * J
dmi = DMI(D)
sim.add(dmi)
Hz = 0.2 * J / const.mu_s_1
zeeman = Zeeman([0, 0, Hz])
sim.add(zeeman)
dt = 2e-14 * 50 # 1e-12
ts = np.linspace(0, 1000 * dt, 501)
for t in ts:
sim.run_until(t)
sim.save_vtk()
sim.save_m()
print 'sim t=%g' % t
def excite_system(T=0.1, H=0.15):
mesh = CuboidMesh(nx=28 * 3, ny=16 * 5, nz=1, pbc='2d')
sim = Sim(mesh, name='dyn', driver='sllg')
sim.set_options(dt=1e-14, gamma=const.gamma, k_B=const.k_B)
sim.alpha = 0.1
sim.mu_s = const.mu_s_1
sim.set_m(random_m)
J = 50 * const.k_B
exch = UniformExchange(J)
sim.add(exch)
D = 0.5 * J
dmi = DMI(D)
sim.add(dmi)
Hz = H * J / const.mu_s_1
zeeman = Zeeman([0, 0, Hz])
sim.add(zeeman)
sim.T = J / const.k_B * T
ts = np.linspace(0, 5e-11, 51)
for t in ts:
sim.run_until(t)
# sim.save_vtk()
np.save('m.npy', sim.spin)
plot_m(mesh, 'm.npy', comp='z')
def excite_system(mesh):
sim = Sim(mesh, name='dyn', driver='sllg')
sim.set_options(dt=1e-14, gamma=const.gamma, k_B=const.k_B)
sim.alpha = 0.1
sim.mu_s = const.mu_s_1
sim.T = temperature_gradient
sim.set_m(np.load("m0.npy"))
J = 50.0 * const.k_B
exch = UniformExchange(J)
sim.add(exch)
D = 0.5 * J
dmi = DMI(D)
sim.add(dmi)
Hz = 0.2 * J / const.mu_s_1
zeeman = Zeeman([0, 0, Hz])
sim.add(zeeman)
dt = 2e-14 * 50 # 1e-12
ts = np.linspace(0, 1000 * dt, 501)
for t in ts:
sim.run_until(t)
sim.save_vtk()
sim.save_m()
print 'sim t=%g' % t
def single_spin(alpha=0.01):
mat = Material()
mesh = CuboidMesh(nx=1, ny=1, nz=1)
sim = Sim(mesh, driver='sllg')
sim.alpha = alpha
sim.gamma = mat.gamma
sim.mu_s = mat.mu_s
sim.T = 10000
sim.set_m((1, 1, 1))
#sim.add(Zeeman(1,(0, 0, 1)))
anis = Anisotropy(mat.K, direction=(0, 0, 1))
sim.add(anis)
dt = 0.5e-12
ts = np.linspace(0, 1000 * dt, 1001)
sx = []
sy = []
for t in ts:
sim.run_until(t)
sx.append(sim.spin[0])
sy.append(sim.spin[1])
print(t)
plt.plot(sx, sy)
plt.xlabel("$S_x$")
plt.ylabel("$S_y$")
plt.grid()
plt.axis((-0.9, 0.9, -0.9, 0.9))
plt.axes().set_aspect('equal')
plt.savefig("macrospin.pdf")
def single_spin(alpha=0.01):
mat = Material()
mesh = CuboidMesh(nx=1, ny=1, nz=1)
sim = Sim(mesh, driver='sllg')
sim.alpha = alpha
sim.gamma = mat.gamma
sim.mu_s = mat.mu_s
sim.T = 10000
sim.set_m((1, 1, 1))
#sim.add(Zeeman(1,(0, 0, 1)))
anis = Anisotropy(mat.K, direction=(0, 0, 1))
sim.add(anis)
dt = 0.5e-12
ts = np.linspace(0, 1000 * dt, 1001)
sx = []
sy = []
for t in ts:
sim.run_until(t)
sx.append(sim.spin[0])
sy.append(sim.spin[1])
print(t)
plt.plot(sx, sy)
plt.xlabel("$S_x$")
plt.ylabel("$S_y$")
plt.grid()
plt.axis((-0.9, 0.9, -0.9, 0.9))
plt.axes().set_aspect('equal')
plt.savefig("macrospin.pdf")