def plot_M_vs_T(ham, supercell_matrix=np.eye(3), Tlist=np.arange(0.0, 110,
20)):
Mlist = []
for temperature in Tlist:
sc_ham = ham.make_supercell(supercell_matrix)
mover = SpinMover(hamiltonian=sc_ham)
mover.set(
time_step=2e-4,
#damping_factor=0.1,
temperature=temperature,
total_time=1,
save_all_spin=True)
mover.run(write_step=10)
hist = mover.get_hist()
hspin = np.array(hist['spin'])
time = np.array(hist['time'])
tspin = np.array(hist['total_spin'])
Ms = np.linalg.det(supercell_matrix)
avg_total_m = np.average((np.linalg.norm(tspin, axis=1) / Ms)[300:])
print("T: %s M: %s" % (temperature, avg_total_m))
Mlist.append(avg_total_m)
plt.plot(Tlist, Mlist)
plt.ylim(-0.01, 1.01)
plt.xlabel('Temperature (K)')
plt.ylabel('Average magnetization (Ms)')
plt.show()
def plot_M_vs_time(ham, supercell_matrix=np.eye(3), temperature=0):
sc_ham = ham.make_supercell(supercell_matrix)
mover = SpinMover(hamiltonian=sc_ham)
mover.set(
time_step=1e-5,
temperature=temperature,
total_time=1,
save_all_spin=True)
mover.run(write_step=10)
hist = mover.get_hist()
hspin = np.array(hist['spin'])
time = np.array(hist['time'])
tspin = np.array(hist['total_spin'])
Ms = np.linalg.det(supercell_matrix)
plt.figure()
plt.plot(
time, np.linalg.norm(tspin, axis=1) / Ms, label='total', color='black')
plt.plot(time, tspin[:, 0] / Ms, label='x')
plt.plot(time, tspin[:, 1] / Ms, label='y')
plt.plot(time, tspin[:, 2] / Ms, label='z')
plt.xlabel('time (s)')
plt.ylabel('magnetic moment ($\mu_B$)')
plt.legend()
#plt.show()
#avg_total_m = np.average((np.linalg.norm(tspin, axis=1)/Ms)[:])
plt.show()
def test_cubic(self):
ham = cubic_3d_hamiltonian(Jx=3e-21, Jy=3e-21, Jz=3e-21)
sc_ham = ham.make_supercell(np.eye(3) * self.N)
mover = SpinMover(hamiltonian=sc_ham,
hist_fname='Spinhist.nc',
write_hist=True)
mover.set(time_step=0.005,
temperature=200.0,
total_time=1,
save_all_spin=False)
mover.run(write_step=10)
def __init__(self, fname=None, sc_matrix=None, ham=None):
self.params = SpinParams()
if ham is not None:
self._ham=ham
elif fname is not None:
self.read_from_file(fname)
else:
self._ham = SpinHamiltonian()
if sc_matrix is not None:
self.make_supercell(sc_matrix)
self.mover = SpinMover(self._ham)
def plot_supercell(ham,
supercell_matrix=np.diag([30, 1, 1]),
plot_type='2d',
length=0.1,
ylimit=None):
sc_ham = ham.make_supercell(supercell_matrix)
sc_ham.s = np.random.rand(*sc_ham.s.shape) - 0.5
mover = SpinMover(hamiltonian=sc_ham)
mover.set(time_step=3e-4, temperature=0, total_time=6, save_all_spin=False)
mover.run(write_step=20)
pos = np.dot(sc_ham.pos, sc_ham.cell)
if plot_type == '2d':
plot_2d_vector(
pos, mover.s, show_z=False, length=length, ylimit=ylimit)
elif plot_type == '3d':
plot_3d_vector(pos, mover.s, length=length)
def make_supercell(self, sc_matrix=None, supercell_maker=None):
self._ham = self._ham.make_supercell(
sc_matrix=sc_matrix, supercell_maker=supercell_maker)
self.mover = SpinMover(self._ham)
return self