# magnetism - Magnetic Models¶

 BaseMagnetism Magnetic properties of the layer. FreeMagnetism Spline change in magnetism throughout layer. Magnetism Region of constant magnetism. MagnetismStack Magnetic slabs within a magnetic layer. MagnetismTwist Linear change in magnetism throughout layer.

Magnetic modeling for 1-D reflectometry.

Magnetic properties are tied to the structural description of the but only loosely.

There may be dead regions near the interfaces of magnetic materials.

Magnetic behaviour may be varying in complex ways within and across structural boundaries. For example, the ma Indeed, the pattern may continue across spacer layers, going to zero in the magnetically dead region and returning to its long range variation on entry to the next magnetic layer. Magnetic multilayers may exhibit complex magnetism throughout the repeated section while the structural components are fixed.

The scattering behaviour is dependent upon net field strength relative to polarization direction. This arises from three underlying quantities: the strength of the individual dipole moments in the layer, the degree of alignment of these moments, and the net direction of the alignment. The strength of the dipole moment depends on the details of the electronic structure, so unlike the nuclear scattering potential, it cannot be readily determined from material composition. Similarly, net magnetization depends on the details of the magnetic domains within the material, and cannot readily be determined from first principles. The interaction potential of the net magnetic moment depends on the alignment of the field with respect to the beam, with a net scattering length density of :math: ho_M cos( heta_M). Clearly the scattering measurement will not be able to distinguish between a reduced net magnetic strength :math: ho_M and a change in orientation :math: heta_M for an individual measurement, as should be apparent from the correlated uncertainty plot produced when both parameters are fit.

Magnetism support is split into two parts: describing the layers and anchoring them to the structure.

class refl1d.magnetism.BaseMagnetism(extent=1, dead_below=0, dead_above=0, interface_below=None, interface_above=None, name='LAYER')[source]

Bases: object

Magnetic properties of the layer.

Magnetism is attached to set of nuclear layers by setting the magnetism property of the first layer to the rendered for the magnetic profile, and setting the magnetism.extent property to say how many layers it extends over.

dead_below and dead_above are dead regions within the magnetic extent, which allow you to shift the magnetic interfaces relative to the nuclear interfaces.

interface_below and interface_above are the interface widths for the magnetic layer, which default to the interface widths for the corresponding nuclear layers if no interfaces are specified. For consecutive layers, only interface_above is used; any value for interface_below is ignored.

parameters()[source]
set_layer_name(name)[source]

Update the names of the magnetic parameters with the name of the layer if it has not already been set. This is necessary since we don’t know the layer name until after we have constructed the magnetism object.

class refl1d.magnetism.FreeMagnetism(z=[], rhoM=[], thetaM=[], name='LAYER', **kw)[source]

Spline change in magnetism throughout layer.

magnetic = True
parameters()[source]
profile(Pz, thickness)[source]
render(probe, slabs, thickness, anchor, sigma)[source]
set_layer_name(name)

Update the names of the magnetic parameters with the name of the layer if it has not already been set. This is necessary since we don’t know the layer name until after we have constructed the magnetism object.

class refl1d.magnetism.Magnetism(rhoM=0, thetaM=270, name='LAYER', **kw)[source]

Region of constant magnetism.

parameters()[source]
render(probe, slabs, thickness, anchor, sigma)[source]
set_layer_name(name)

Update the names of the magnetic parameters with the name of the layer if it has not already been set. This is necessary since we don’t know the layer name until after we have constructed the magnetism object.

class refl1d.magnetism.MagnetismStack(weight=[], rhoM=[], thetaM=[270], interfaceM=[0], name='LAYER', **kw)[source]

Magnetic slabs within a magnetic layer.

parameters()[source]
render(probe, slabs, thickness, anchor, sigma)[source]
set_layer_name(name)

Update the names of the magnetic parameters with the name of the layer if it has not already been set. This is necessary since we don’t know the layer name until after we have constructed the magnetism object.

class refl1d.magnetism.MagnetismTwist(rhoM=[0, 0], thetaM=[270, 270], name='LAYER', **kw)[source]

Linear change in magnetism throughout layer.

magnetic = True
parameters()[source]
render(probe, slabs, thickness, anchor, sigma)[source]
set_layer_name(name)

Update the names of the magnetic parameters with the name of the layer if it has not already been set. This is necessary since we don’t know the layer name until after we have constructed the magnetism object.