def calculate(self, state, id):
cache = state.cache
if id == "dMdt_ST":
if hasattr(cache, "dMdt_ST"):
return cache.dMdt_ST
dMdt_ST = cache.dMdt_ST = VectorField(self.system.mesh)
# Calculate spin torque term due to Zhang & Li
nx, ny, nz = self.system.mesh.num_nodes
dx, dy, dz = self.system.mesh.delta
magneto.fdm_zhangli(
nx,
ny,
nz,
dx,
dy,
dz,
self.__do_precess,
self.P,
self.xi,
self.system.Ms,
self.system.alpha,
state.j,
state.M,
dMdt_ST,
)
return dMdt_ST
else:
raise KeyError("SpinTorque.calculate: Can't calculate %s", id)
def with_zero_gradient_test(self, dim_x, dim_y, dim_z, uniform):
self.setup_stuff(dim_x, dim_y, dim_z, uniform)
# No gradient in M -> no spin torque
self.M.fill((0.0, 0.0, 0.0))
magneto.fdm_zhangli(self.dim_x, self.dim_y, self.dim_z, self.delta_x,
self.delta_y, self.delta_z, True, self.P, self.xi,
self.Ms, self.alpha, self.J, self.M, self.dM)
self.assertFloatTupleEq((0.0, 0.0, 0.0),
self.dM.average(),
epsilon=0.001) # spin torque is zero
def with_zero_gradient_test(self, dim_x, dim_y, dim_z, uniform):
self.setup_stuff(dim_x, dim_y, dim_z, uniform)
# No gradient in M -> no spin torque
self.M.fill((0.0, 0.0, 0.0))
magneto.fdm_zhangli(
self.dim_x, self.dim_y, self.dim_z, self.delta_x, self.delta_y, self.delta_z, True,
self.P, self.xi,
self.Ms, self.alpha,
self.J, self.M, self.dM
)
self.assertFloatTupleEq((0.0, 0.0, 0.0), self.dM.average(), epsilon=0.001) # spin torque is zero
def with_vortex_test(self, dim_x, dim_y, dim_z, uniform):
self.setup_stuff(dim_x, dim_y, dim_z, uniform)
vortex_fn = vortex.magnetizationFunction(150e-9, 150e-9)
for n in range(self.mesh.total_nodes):
x, y, z = self.mesh.getPosition(n)
self.M.set(n, vortex_fn(self.M, (x, y, z)))
magneto.fdm_zhangli(
self.dim_x, self.dim_y, self.dim_z, self.delta_x, self.delta_y, self.delta_z, True,
self.P, self.xi,
self.Ms, self.alpha,
self.J, self.M, self.dM
)
ref_avg = (340104691300.73352, 337831145947.55255, 7.4024200439453129e-06)
#print("Reference <dM>: ", ref_avg)
#print("Actual <dM>: ", self.dM.average())
# epsilon must be relatively big...
self.assertFloatTupleEq(self.dM.average(), ref_avg, epsilon=1000000.0)
