mag2exp.sans.chiral_function#
- mag2exp.sans.chiral_function(field, /, polarisation=(0, 0, 1))#
Calculation of the chiral function \(-2\pi i \chi\).
The chiral function can be calculated using
\[-2\pi i \chi = \frac{d\sum^{+-}}{d\Omega} - \frac{d\sum^{-+}}{d\Omega}\]where \(\frac{d\sum^{+-}}{d\Omega}\) and \(\frac{d\sum^{-+}}{d\Omega}\) are the spin-flip cross sections.
Note that this function returns the quantity \(-2\pi i \chi\).
- Parameters:
field (discretisedfield.field) – Magnetisation field.
polarisation (turple) – Defines the polarisation direction of the incoming reutron beam with respect to the sample reference frame.
- Returns:
Chiral function \(-2\pi i \chi\).
- Return type:
Examples
Visualising the chiral function with
matplotlib
.
>>> import discretisedfield as df >>> import micromagneticmodel as mm >>> import numpy as np >>> import mag2exp >>> mesh = df.Mesh(p1=(-25e-9, -25e-9, -25e-9), ... p2=(25e-9, 25e-9, 25e-9), ... cell=(1e-9, 1e-9, 1e-9)) >>> def v_fun(point): ... x, y, z = point ... q = 10e-9 ... return (0, ... np.sin(2 * np.pi * x / q), ... np.cos(2 * np.pi * x / q)) >>> field = df.Field(mesh, nvdim=3, value=v_fun, norm=1e5) >>> field.sel('z').mpl() >>> cf = mag2exp.sans.chiral_function(field, ... polarisation=(1, 0, 0)) >>> cf.sel(k_z=0).mpl.scalar()