def relax_system(mesh): sim = Sim(mesh, name='relax') sim.driver.set_tols(rtol=1e-10, atol=1e-14) sim.driver.alpha = 0.5 sim.driver.gamma = 2.211e5 sim.Ms = spatial_Ms sim.driver.do_precession = False sim.set_m(init_m) # sim.set_m(np.load('m0.npy')) A = 1.3e-11 exch = UniformExchange(A=A) sim.add(exch) demag = Demag(pbc_2d=True) sim.add(demag) mT = 795.7747154594767 ONE_DEGREE_PER_NS = 17453292.52 sim.relax(dt=1e-13, stopping_dmdt=0.01, max_steps=5000, save_m_steps=100, save_vtk_steps=50) np.save('m0.npy', sim.spin)
def run_fidimag(mesh): mu0 = 4 * np.pi * 1e-7 Ms = 8.6e5 A = 16e-12 D = -3.6e-3 K = 510e3 sim = Sim(mesh) sim.set_tols(rtol=1e-10, atol=1e-10) sim.alpha = 0.5 sim.gamma = 2.211e5 sim.Ms = Ms sim.do_precession = False sim.set_m((0, 0, 1)) sim.add(UniformExchange(A)) sim.add(DMI(D, dmi_type='interfacial')) sim.add(UniaxialAnisotropy(K, axis=(0, 0, 1))) sim.relax(dt=1e-13, stopping_dmdt=0.01, max_steps=5000, save_m_steps=None, save_vtk_steps=50) m = sim.spin return m.copy()
def relax_system(mesh): sim = Sim(mesh, name='relax') sim.driver.set_tols(rtol=1e-10, atol=1e-10) sim.driver.alpha = 0.5 sim.driver.gamma = 2.211e5 sim.Ms = 8.0e5 sim.do_precession = False sim.set_m((1, 0.25, 0.1)) # sim.set_m(np.load('m0.npy')) A = 1.3e-11 exch = UniformExchange(A=A) sim.add(exch) demag = Demag() sim.add(demag) sim.relax(dt=1e-13, stopping_dmdt=0.01, max_steps=5000, save_m_steps=100, save_vtk_steps=50) np.save('m0.npy', sim.spin)
def relax_system(mesh): sim = Sim(mesh, name='relax') sim.driver.set_tols(rtol=1e-6, atol=1e-6) sim.driver.alpha = 0.5 sim.driver.gamma = 2.211e5 sim.Ms = 8.6e5 sim.do_precession = False sim.set_m(init_m) exch = UniformExchange(A=1.3e-11) sim.add(exch) dmi = DMI(D=-4e-3) sim.add(dmi) zeeman = Zeeman((0, 0, 4e5)) sim.add(zeeman, save_field=True) sim.relax(dt=1e-13, stopping_dmdt=1e-2, save_m_steps=None, save_vtk_steps=50) np.save('m0.npy', sim.spin)
def test_dw_dmi(mesh=mesh, do_plot=False): Ms = 8.0e5 sim = Sim(mesh, name='relax') sim.set_m(m_init_dw) sim.set_tols(rtol=1e-8, atol=1e-12) sim.Ms = Ms sim.alpha = 0.5 sim.do_procession = False A = 1.3e-11 D = 4e-4 Kx = 8e4 Kp = -6e5 sim.add(UniformExchange(A)) sim.add(DMI(D)) sim.add(UniaxialAnisotropy(Kx, axis=[1, 0, 0], name='Kx')) sim.relax(stopping_dmdt=0.01) xs = np.array([p[0] for p in mesh.coordinates]) mx, my, mz = analytical(xs, A=A, D=D, K=Kx) mxyz = sim.spin.copy() mxyz = mxyz.reshape(-1, 3) assert max(abs(mxyz[:, 0] - mx)) < 0.002 assert max(abs(mxyz[:, 1] - my)) < 0.002 assert max(abs(mxyz[:, 2] - mz)) < 0.0006 if do_plot: save_plot(mxyz, mx, my, mz)
def relax_system(mesh): sim = Sim(mesh, name='relax') sim.set_tols(rtol=1e-6, atol=1e-6) sim.alpha = 0.5 sim.gamma = 2.211e5 sim.Ms = 8.6e5 sim.do_precession = False sim.set_m(init_m) exch = UniformExchange(A=1.3e-11) sim.add(exch) dmi = DMI(D=-4e-3) sim.add(dmi) zeeman = Zeeman((0, 0, 4e5)) sim.add(zeeman, save_field=True) sim.relax(dt=1e-13, stopping_dmdt=1e-2, save_m_steps=None, save_vtk_steps=50) np.save('m0.npy', sim.spin)
def relax_system(mesh): sim = Sim(mesh, name='relax') sim.set_tols(rtol=1e-6, atol=1e-6) sim.alpha = 0.5 sim.gamma = 2.211e5 sim.Ms = 8.6e5 sim.do_precession = False sim.set_m(init_m) #sim.set_m((0,0.1,1)) #sim.set_m(np.load('m0.npy')) A = 1.3e-11 exch = UniformExchange(A=A) sim.add(exch) dmi = DMI(D=1.3e-3) sim.add(dmi) anis = UniaxialAnisotropy(-3.25e4, axis=(0, 0, 1)) sim.add(anis) zeeman = Zeeman((0, 0, 6.014576e4)) sim.add(zeeman, save_field=True) sim.relax(dt=1e-13, stopping_dmdt=0.5, max_steps=5000, save_m_steps=None, save_vtk_steps=50) np.save('m0.npy', sim.spin)
def relax_system(mesh): # Only relaxation sim = Sim(mesh, name='relax') # Simulation parameters sim.set_tols(rtol=1e-8, atol=1e-10) sim.alpha = 0.5 sim.gamma = 2.211e5 sim.Ms = 8.6e5 sim.do_procession = False # The initial state passed as a function sim.set_m(init_m) # sim.set_m(np.load('m0.npy')) # Energies A = 1.3e-11 exch = UniformExchange(A=A) sim.add(exch) anis = UniaxialAnisotropy(5e4) sim.add(anis) # dmi = DMI(D=8e-4) # sim.add(dmi) # Start relaxation and save the state in m0.npy sim.relax(dt=1e-14, stopping_dmdt=0.00001, max_steps=5000, save_m_steps=None, save_vtk_steps=None) np.save('m0.npy', sim.spin)
def relax_system(mesh): sim = Sim(mesh, name='relax') sim.set_tols(rtol=1e-10, atol=1e-14) sim.alpha = 0.5 sim.gamma = 2.211e5 sim.Ms = 8.6e5 sim.do_precession = False sim.set_m((1,1,1)) # sim.set_m(np.load('m0.npy')) A = 1.3e-11 exch = UniformExchange(A=A) sim.add(exch) dmi = DMI(D=1e-3) sim.add(dmi) zeeman = Zeeman((0, 0, 2e4)) sim.add(zeeman, save_field=True) sim.relax(dt=1e-13, stopping_dmdt=0.01, max_steps=5000, save_m_steps=None, save_vtk_steps=50) np.save('m0.npy', sim.spin)
def relax_system(mesh): # Only relaxation sim = Sim(mesh, name='relax') # Simulation parameters sim.driver.set_tols(rtol=1e-8, atol=1e-10) sim.driver.alpha = 0.5 sim.driver.gamma = 2.211e5 sim.Ms = 8.6e5 sim.do_precession = False # The initial state passed as a function sim.set_m(init_m) # sim.set_m(np.load('m0.npy')) # Energies A = 1.3e-11 exch = UniformExchange(A=A) sim.add(exch) anis = UniaxialAnisotropy(5e4) sim.add(anis) # Start relaxation and save the state in m0.npy sim.relax(dt=1e-14, stopping_dmdt=0.00001, max_steps=5000, save_m_steps=None, save_vtk_steps=None) np.save('m0.npy', sim.spin)
def relax_system(mesh): sim = Sim(mesh, name="relax") sim.driver.set_tols(rtol=1e-10, atol=1e-14) sim.driver.alpha = 0.5 sim.driver.gamma = 2.211e5 sim.Ms = 8.6e5 sim.do_precession = False sim.set_m(init_m) # sim.set_m(np.load('m0.npy')) A = 1.3e-11 exch = UniformExchange(A=A) sim.add(exch) dmi = DMI(D=1e-3) sim.add(dmi) zeeman = Zeeman((0, 0, 2e4)) sim.add(zeeman, save_field=True) sim.relax(dt=1e-13, stopping_dmdt=0.01, max_steps=5000, save_m_steps=None, save_vtk_steps=50) np.save("m0.npy", sim.spin)
def run_fidimag(mesh): mu0 = 4 * np.pi * 1e-7 Ms = 8.6e5 A = 16e-12 D = -3.6e-3 K = 510e3 sim = Sim(mesh) sim.set_tols(rtol=1e-10, atol=1e-10) sim.alpha = 0.5 sim.gamma = 2.211e5 sim.Ms = Ms sim.do_precession = False sim.set_m((0, 0, 1)) sim.add(UniformExchange(A)) sim.add(DMI(D, type='interfacial')) sim.add(UniaxialAnisotropy(K, axis=(0, 0, 1))) sim.relax(dt=1e-13, stopping_dmdt=0.01, max_steps=5000, save_m_steps=None, save_vtk_steps=50) m = sim.spin return m.copy()
def relax_system(mesh): sim = Sim(mesh, chi=1e-3, name='relax', driver='llbar_full') sim.set_tols(rtol=1e-7, atol=1e-7) sim.Ms = 8.0e5 sim.alpha = 0.1 sim.beta = 0 sim.gamma = 2.211e5 sim.set_m((1, 0.25, 0.1)) # sim.set_m(np.load('m0.npy')) A = 1.3e-11 exch = UniformExchange(A=A) sim.add(exch) mT = 795.7747154594767 zeeman = Zeeman([-100 * mT, 4.3 * mT, 0], name='H') sim.add(zeeman, save_field=True) demag = Demag() sim.add(demag) ONE_DEGREE_PER_NS = 17453292.52 sim.relax(dt=1e-12, stopping_dmdt=0.01, max_steps=5000, save_m_steps=100, save_vtk_steps=50) np.save('m0.npy', sim.spin)
def test_dw_dmi(mesh=mesh, do_plot=False): Ms = 8.0e5 sim = Sim(mesh, name='relax') sim.set_m(m_init_dw) sim.set_tols(rtol=1e-8, atol=1e-12) sim.Ms = Ms sim.alpha = 0.5 sim.do_precession = False A = 1.3e-11 D = 4e-4 Kx = 8e4 Kp = -6e5 sim.add(UniformExchange(A)) sim.add(DMI(D)) sim.add(UniaxialAnisotropy(Kx, axis=[1, 0, 0], name='Kx')) sim.relax(stopping_dmdt=0.01) xs = np.array([p[0] for p in mesh.coordinates]) mx, my, mz = analytical(xs, A=A, D=D, K=Kx) mxyz = sim.spin.copy() mxyz = mxyz.reshape(-1, 3) assert max(abs(mxyz[:, 0] - mx)) < 0.002 assert max(abs(mxyz[:, 1] - my)) < 0.002 assert max(abs(mxyz[:, 2] - mz)) < 0.0006 if do_plot: save_plot(mxyz, mx, my, mz)
def relax_system(mesh): sim = Sim(mesh, chi=1e-3, name='relax', driver='llbar_full') sim.driver.set_tols(rtol=1e-7, atol=1e-7) sim.Ms = 8.0e5 sim.driver.alpha = 0.1 sim.beta = 0 sim.driver.gamma = 2.211e5 sim.set_m((1, 0.25, 0.1)) # sim.set_m(np.load('m0.npy')) A = 1.3e-11 exch = UniformExchange(A=A) sim.add(exch) mT = 795.7747154594767 zeeman = Zeeman([-100 * mT, 4.3 * mT, 0], name='H') sim.add(zeeman, save_field=True) demag = Demag() sim.add(demag) ONE_DEGREE_PER_NS = 17453292.52 sim.relax(dt=1e-12, stopping_dmdt=0.01, max_steps=5000, save_m_steps=100, save_vtk_steps=50) np.save('m0.npy', sim.spin)
def relax_system(mesh): sim = Sim(mesh, name='relax') sim.driver.set_tols(rtol=1e-10, atol=1e-10) sim.driver.alpha = 0.1 sim.driver.gamma = 2.211e5 sim.Ms = spatial_Ms print(sim.Ms) sim.set_m(init_m) A = 1.3e-11 exch = UniformExchange(A=A) sim.add(exch) demag = Demag() sim.add(demag) dmi = DMI(D=4e-3) sim.add(dmi) dmi2 = DMI(D=2e-3, dmi_type="interfacial") sim.add(dmi2) anis = UniaxialAnisotropy(-3e4, axis=(0, 0, 1)) sim.add(anis) sim.relax(dt=1e-13, stopping_dmdt=5e4, max_steps=5000, save_m_steps=100, save_vtk_steps=50) #np.save('m0.npy', sim.spin) fd = demag.compute_field(sim.spin) fe = exch.compute_field(sim.spin) fdmi = dmi.compute_field(sim.spin) fdmi2 = dmi2.compute_field(sim.spin) fanis = anis.compute_field(sim.spin) np.savetxt( "test_fields.txt", np.transpose([ np.concatenate((sim.Ms, sim.Ms, sim.Ms, [0.0])), np.concatenate((sim.spin, [100])), np.concatenate((fd, [demag.compute_energy()])), np.concatenate((fe, [exch.compute_energy()])), np.concatenate((fdmi, [dmi.compute_energy()])), np.concatenate((fdmi2, [dmi2.compute_energy()])), np.concatenate((fanis, [anis.compute_energy()])) ]), header= "Generated by Fidimag. Size=20x5x3, 2.5nm x 2.5nm x 3nm, Ms=8.0e5A/m, A=1.3e-11 J/m," + " D=4e-3 J/m^2, D_int=2e-3 J/m^2, Ku=-3e4 J/m^3 axis=(0,0,1).\n Ms " + "".ljust(20) + " m0 " + "".ljust(20) + "demag" + "".ljust(20) + "exch" + "".ljust(22) + "dmi" + "".ljust(22) + "dmi_interfacial" + "".ljust(22) + "anis")
def relax_system_only_exchange(mesh): sim = Sim(mesh, name='relax_exchange_only') sim.set_tols(rtol=1e-6, atol=1e-6) sim.alpha = 0.5 sim.gamma = 2.211e5 sim.Ms = 8.6e5 sim.do_procession = False sim.set_m(init_m_BP) A = 1.3e-11 exch = UniformExchange(A=A) sim.add(exch) sim.relax(dt=1e-13, stopping_dmdt=0.5, max_steps=5000, save_m_steps=None, save_vtk_steps=50) np.save('m0.npy', sim.spin)
def relax_system_only_exchange(mesh): sim = Sim(mesh, name='relax_exchange_only') sim.set_tols(rtol=1e-6, atol=1e-6) sim.alpha = 0.5 sim.gamma = 2.211e5 sim.Ms = 8.6e5 sim.do_precession = False sim.set_m(init_m_BP) A = 1.3e-11 exch = UniformExchange(A=A) sim.add(exch) sim.relax(dt=1e-13, stopping_dmdt=0.5, max_steps=5000, save_m_steps=None, save_vtk_steps=50) np.save('m0.npy', sim.spin)
def relax_system(mesh): sim = Sim(mesh, name='relax') sim.set_tols(rtol=1e-10, atol=1e-10) sim.alpha = 0.5 sim.gamma = 2.211e5 sim.Ms = 8.0e5 sim.do_precession = False sim.set_m((1, 0.25, 0.1)) # sim.set_m(np.load('m0.npy')) A = 1.3e-11 exch = UniformExchange(A=A) sim.add(exch) demag = Demag() sim.add(demag) sim.relax(dt=1e-13, stopping_dmdt=0.01, max_steps=5000, save_m_steps=100, save_vtk_steps=50) np.save('m0.npy', sim.spin)
m = m.reshape(3, -1).T[top_z] quiv.set_UVC(m[:, 0], m[:, 1], m[:, 2]) # Update title ttime.set_text('Time: {:.4f} ns'.format(time * 1e9)) tenergy.set_text('Energy: {:.6e} ns'.format(sim.compute_energy())) # fig.show() fig.canvas.draw() else: # Fidimag automatically saves the last state sim.do_precession = False sim.relax(dt=1e-13, stopping_dmdt=args.stopping_dmdt, max_steps=args.max_steps, save_m_steps=args.save_files, save_vtk_steps=args.save_files) # Save final states sim.save_m() sim.save_vtk() # ------------------------------------------------------------------------- # Files ------------------------------------------------------------------- # ------------------------------------------------------------------------- npy_dir = 'npys/' vtk_dir = 'vtks/' txt_dir = 'txts/'
# reshape rows, transpose and filter according to top layer m = m.reshape(3, -1).T[top_z] quiv.set_UVC(m[:, 0], m[:, 1], m[:, 2]) # Update title ttime.set_text('Time: {:.4f} ns'.format(time * 1e9)) tenergy.set_text('Energy: {:.6e} ns'.format(sim.compute_energy())) # fig.show() fig.canvas.draw() else: # Fidimag automatically saves the last state sim.do_precession = False sim.relax(dt=1e-13, stopping_dmdt=args.stopping_dmdt, max_steps=args.max_steps, save_m_steps=args.save_files, save_vtk_steps=args.save_files) # Save final states sim.save_m() sim.save_vtk() # ------------------------------------------------------------------------- # Files ------------------------------------------------------------------- # ------------------------------------------------------------------------- npy_dir = 'npys/' vtk_dir = 'vtks/' txt_dir = 'txts/'
if x < 450: return (1, 0, 0) elif 450 <= x < 550: return (0, 1, 1) else: return (-1, 0, 0) sim = Sim(mesh) sim.alpha = alpha sim.gamma = gamma sim.Ms = Ms sim.add(UniformExchange(A)) sim.add(UniaxialAnisotropy(K)) sim.set_m(init_m) sim.relax(dt=1e-13, stopping_dmdt=0.001, max_steps=5000) # Magnetisation x component. mx_simulation = sim.spin.reshape((len(sim.spin) / 3, 3))[:, 0] ################### # Analytic solution ################### d = 1000e-9 # sample length (nm) n_points = 500 mx_analytic = domain_wall_analytic_solution(A, K, d, n_points) ################### # Plot solutions ################### plt.figure(figsize=(8, 5))
# Prepare simulation # We define the cylinder with the Magnetisation function sim = Sim(mesh, name='skyrmion') sim.Ms = cylinder # To get a faster relaxation, we tune the LLG equation parameters sim.do_precession = False sim.alpha = 0.5 # Initial magnetisation: sim.set_m(init_m) # Energies: # Exchange sim.add(UniformExchange(A=A)) # Bulk DMI sim.add(DMI(D=D)) # Relax the system sim.relax(dt=1e-12, stopping_dmdt=0.0001, max_steps=5000, save_m_steps=None, save_vtk_steps=None ) # Save the final relaxed state and a vtk file np.save('sk_up.npy', sim.spin) sim.save_vtk()
# We define the cylinder with the Magnetisation function sim = Sim(mesh, name='skyrmion') sim.Ms = cylinder # To get a faster relaxation, we tune the LLG equation parameters sim.do_precession = False sim.alpha = 0.5 # Initial magnetisation: sim.set_m(init_m) # Energies: # Exchange sim.add(UniformExchange(A=A)) # Bulk DMI sim.add(DMI(D=D)) # Relax the system sim.relax(dt=1e-12, stopping_dmdt=0.0001, max_steps=5000, save_m_steps=None, save_vtk_steps=None) # Save the final relaxed state and a vtk file np.save('sk_up.npy', sim.spin) sim.save_vtk()
sim.add(fidimag.micro.UniformExchange(A)) sim.add(fidimag.micro.UniaxialAnisotropy(Ku, axis=(0, 0, 1))) sim.add(fidimag.micro.Zeeman((0, 0, Bz / C.mu_0))) # sim.add(fidimag.micro.DMI(D, dmi_type='interfacial')) # For a C_n material, there is a kind of instability when one of the DM # constants is larger than approx 0.7 times the other DM constant sim.add(fidimag.micro.DMI([D, 0.6 * D], dmi_type='C_n')) sim.set_m(init_m) sim.driver.do_precession = False sim.driver.alpha = 0.9 sim.relax() # ---------------------------------------------------------------------------- # Plot the 2D system import matplotlib.pyplot as plt m = sim.spin.reshape(-1, 3) plt.figure(figsize=(8, 8)) plt.quiver(mesh.coordinates[:, 0], mesh.coordinates[:, 1], m[:, 0], m[:, 1], m[:, 2], cmap='RdYlBu') plt.show()