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#!/usr/bin/env python3
# /// script
# requires-python = ">=3.10"
# dependencies = ["bornagain>=25,<26"]
# ///
"""
Polarized neutron reflectometry from a CoFe/IrMn stripe-domain stack.
The layer structure follows Saerbeck et al., Nanomaterials 10, 752 (2020).
The specular model uses a laterally averaged magnetic slab description.
"""
from math import cos, sin
import numpy as np
import bornagain as ba
ba.require_versions("bornagain>=25,<26")
from bornagain import R3, deg, nm
colors = {
"TaOx": (0.72, 0.72, 0.72),
"Ta": (0.45, 0.45, 0.48),
"CoFe": (0.48, 0.32, 0.80),
"IrMn": (0.86, 0.24, 0.18),
"Cu": (0.94, 0.54, 0.20),
"SiO2": (0.28, 0.57, 0.82),
"Si": (0.35, 0.35, 0.35),
}
sld = {
"TaOx": (5.54e-6, 3.3e-9),
"Ta": (3.52e-6, 3.3e-9),
"CoFe": (4.17e-6, 3.7e-9),
"IrMn": (-0.74e-6, 18.2e-9),
"Cu": (5.57e-6, 0.7e-9),
"SiO2": (3.66e-6, 0.012e-9),
"Si": (2.10e-6, 0.023e-9),
}
thickness = {
"TaOx": 3.1*nm,
"Ta": 8.3*nm,
"CoFe": 6.1*nm,
"IrMn": 29.6*nm,
"Cu": 3.7*nm,
"SiO2": 1.0*nm,
"Si": None,
}
roughness_rms = {
"TaOx": 1.7*nm,
"Ta": 0.5*nm,
"CoFe": 1.3*nm,
"IrMn": 1.5*nm,
"Cu": 1.2*nm,
"SiO2": 1.4*nm,
"Si": 0.4*nm,
}
def B(Bmag, Bangle_deg):
Bangle = Bangle_deg*deg
return R3(Bmag*sin(Bangle), Bmag*cos(Bangle), 0)
def get_sample(magnetic_scale):
transient = ba.ErfTransient()
hurst = 0.3
corr_length = 5*nm
cofe_field = B(magnetic_scale*1.71e6, 0)
irmn_field = B(magnetic_scale*42e3, 0)
material_taox = ba.SLDMaterial("TaOx", colors["TaOx"], *sld["TaOx"])
material_ta = ba.SLDMaterial("Ta", colors["Ta"], *sld["Ta"])
material_cofe = ba.SLDMaterial("CoFe", colors["CoFe"], *sld["CoFe"], cofe_field)
material_irmn = ba.SLDMaterial("IrMn", colors["IrMn"], *sld["IrMn"], irmn_field)
material_cu = ba.SLDMaterial("Cu", colors["Cu"], *sld["Cu"])
material_sio2 = ba.SLDMaterial("SiO2", colors["SiO2"], *sld["SiO2"])
material_si = ba.SLDMaterial("Si", colors["Si"], *sld["Si"])
sample = ba.Sample()
sample.addLayer(ba.Layer(ba.Vacuum()))
autocorr = ba.SelfAffineFractalModel(roughness_rms["TaOx"], hurst, corr_length)
roughness = ba.Roughness(autocorr, transient)
sample.addLayer(ba.Layer(material_taox, thickness["TaOx"], roughness))
autocorr = ba.SelfAffineFractalModel(roughness_rms["Ta"], hurst, corr_length)
roughness = ba.Roughness(autocorr, transient)
sample.addLayer(ba.Layer(material_ta, thickness["Ta"], roughness))
autocorr = ba.SelfAffineFractalModel(roughness_rms["CoFe"], hurst, corr_length)
roughness = ba.Roughness(autocorr, transient)
sample.addLayer(ba.Layer(material_cofe, thickness["CoFe"], roughness))
autocorr = ba.SelfAffineFractalModel(roughness_rms["IrMn"], hurst, corr_length)
roughness = ba.Roughness(autocorr, transient)
sample.addLayer(ba.Layer(material_irmn, thickness["IrMn"], roughness))
autocorr = ba.SelfAffineFractalModel(roughness_rms["Cu"], hurst, corr_length)
roughness = ba.Roughness(autocorr, transient)
sample.addLayer(ba.Layer(material_cu, thickness["Cu"], roughness))
autocorr = ba.SelfAffineFractalModel(roughness_rms["SiO2"], hurst, corr_length)
roughness = ba.Roughness(autocorr, transient)
sample.addLayer(ba.Layer(material_sio2, thickness["SiO2"], roughness))
autocorr = ba.SelfAffineFractalModel(roughness_rms["Si"], hurst, corr_length)
roughness = ba.Roughness(autocorr, transient)
sample.addLayer(ba.Layer(material_si, roughness))
return sample
def simulate(magnetic_scale, polarization, title):
n = 500
qzs = np.linspace(0.05/nm, 1.5/nm, n)
distr = ba.DistributionGaussian(0, 1, 25, 4)
scan = ba.QzScan(qzs)
scan.setAbsoluteQResolution(distr, 0.001/nm)
scan.setPolarization(polarization)
simulation = ba.SpecularSimulation(scan, get_sample(magnetic_scale))
simulation.setBackground(ba.ConstantBackground(1e-7))
result = simulation.simulate()
result.setTitle(title)
return result
if __name__ == '__main__':
ba.showSample3D(get_sample(1), sample_size=80*nm, seed=0)
results = [
simulate(1, R3(0, +1, 0), "saturated R+"),
simulate(1, R3(0, -1, 0), "saturated R-"),
simulate(0, R3(0, +1, 0), "demagnetized R+"),
]
ba.plot_multicurve(results)
ba.plt.show()
|
BornAgain
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≻ Documentation ≻ Examples ≻ Specular ≻ Magnetic and polarized ≻ Stripe domains reflectivity
