Dynamics of macrospin

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import oommfc as oc
import discretisedfield as df
%matplotlib inline


    

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# define macro spin (i.e. one discretisation cell)
p1 = (0, 0, 0)            # all lengths in metre
p2 = (5e-9, 5e-9, 5e-9)
cell = (5e-9, 5e-9, 5e-9)
mesh = oc.Mesh(p1=p1, p2=p2, cell=cell)

initial_m = (1, 0, 0)     # vector in x direction
Ms = 8e6  # magnetisation saturation (A/m)
m = df.Field(mesh, value=initial_m, norm=Ms)


    

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zeeman = oc.Zeeman(H=(0, 0, -5e6)) # external magnetic field (A/m)


    

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gamma = 2.211e5  # gyrotropic ration
alpha = 0.05 # Gilbert damping

system = oc.System(name="macrospin")
system.hamiltonian = zeeman
system.m = m
system.dynamics = oc.Precession(gamma) + oc.Damping(alpha)


    

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td = oc.TimeDriver()
td.drive(system, t=0.1e-9, n=200)


    

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d = system.dt    # pure convenience: DataTable -> d


    

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