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// ************************************************************************************************
//
// BornAgain: simulate and fit reflection and scattering
//
//! @file Sample/StandardSample/FeNiBilayerBuilder.cpp
//! @brief Defines various sample builder classes to.
//! test polarized specular computations
//!
//! @homepage http://www.bornagainproject.org
//! @license GNU General Public License v3 or higher (see COPYING)
//! @copyright Forschungszentrum Jülich GmbH 2020
//! @authors Scientific Computing Group at MLZ (see CITATION, AUTHORS)
//
// ************************************************************************************************
#include "Sample/StandardSample/FeNiBilayerBuilder.h"
#include "Base/Const/PhysicalConstants.h"
#include "Base/Const/Units.h"
#include "Sample/Interface/Roughness.h"
#include "Sample/Material/MaterialFactoryFuncs.h"
#include "Sample/Multilayer/Layer.h"
#include "Sample/Multilayer/Sample.h"
using Units::deg;
namespace {
auto constexpr rhoMconst = -PhysConsts::m_n * PhysConsts::g_factor_n * PhysConsts::mu_N
/ PhysConsts::h_bar / PhysConsts::h_bar * 1e-27;
const complex_t sldFe = complex_t{8.02e-06, 0};
const complex_t sldAu = complex_t{4.6665e-6, 0};
const complex_t sldNi = complex_t{9.4245e-06, 0};
class Options {
public:
int m_NBilayers = 4;
double m_angle = 0.;
double m_magnetization_magnitude = 1e7;
double m_thickness_fe = 100. * Units::angstrom;
double m_thickness_ni = 40. * Units::angstrom;
double m_sigma_roughness = 0.;
int m_effectiveSLD = 0;
std::unique_ptr<TransientModel> m_transient = std::make_unique<ErfTransient>();
Options() = default;
void setNBilayers(int n) { m_NBilayers = n; }
void setAngle(double angle) { m_angle = angle; }
void setMagnetizationMagnitude(double M) { m_magnetization_magnitude = M; }
void setThicknessFe(double t) { m_thickness_fe = t; }
void setThicknessNi(double t) { m_thickness_ni = t; }
void setSigmaRoughness(double r) { m_sigma_roughness = r; }
void setEffectiveSLD(int i) { m_effectiveSLD = i; }
void setTransientModel(TransientModel* im) { m_transient.reset(im); }
};
//! Creates the sample demonstrating an Fe-Ni Bilayer with and without roughness
class FeNiBilayer {
public:
explicit FeNiBilayer(Options opt = {})
: NBilayers(opt.m_NBilayers)
, angle(opt.m_angle)
, magnetizationMagnitude(opt.m_magnetization_magnitude)
, thicknessFe(opt.m_thickness_fe)
, thicknessNi(opt.m_thickness_ni)
, sigmaRoughness(opt.m_sigma_roughness)
, effectiveSLD(opt.m_effectiveSLD)
, transient(opt.m_transient ? opt.m_transient->clone() : nullptr)
{
if (angle != 0. && effectiveSLD != 0.)
throw std::runtime_error("Cannot perform scalar computation "
"for non-colinear magnetization");
magnetizationVector = R3(magnetizationMagnitude * std::sin(angle),
magnetizationMagnitude * std::cos(angle), 0);
sample = constructSample();
}
Sample* release() { return sample.release(); }
private:
int NBilayers;
double angle;
double magnetizationMagnitude;
double thicknessFe;
double thicknessNi;
double sigmaRoughness;
int effectiveSLD;
std::unique_ptr<TransientModel> transient;
R3 magnetizationVector;
std::unique_ptr<Sample> sample;
std::unique_ptr<Sample> constructSample();
};
std::unique_ptr<Sample> FeNiBilayer::constructSample()
{
auto result = std::make_unique<Sample>();
auto m_ambient = MaterialBySLD("Ambient", 0.0, 0.0);
auto m_Fe =
effectiveSLD == 0
? MaterialBySLD("Fe", sldFe.real(), sldFe.imag(), magnetizationVector)
: MaterialBySLD("Fe", sldFe.real() + effectiveSLD * rhoMconst * magnetizationMagnitude,
sldFe.imag(), R3());
auto m_Ni = MaterialBySLD("Ni", sldNi.real(), sldNi.imag());
auto m_Substrate = MaterialBySLD("Au", sldAu.real(), sldAu.imag());
SelfAffineFractalModel autocorrelation(sigmaRoughness, 0.7, 25);
Roughness roughness{&autocorrelation, transient.get()};
Layer l_Fe{m_Fe, thicknessFe, &roughness};
Layer l_Ni{m_Ni, thicknessNi, &roughness};
result->addLayer(Layer{m_ambient});
for (auto i = 0; i < NBilayers; ++i) {
result->addLayer(l_Fe);
result->addLayer(l_Ni);
}
result->addLayer(Layer{m_Substrate, &roughness});
return result;
}
} // namespace
Sample* ExemplarySamples::createFeNiBilayer()
{
auto sample = FeNiBilayer{Options()};
return sample.release();
}
Sample* ExemplarySamples::createFeNiBilayerTanh()
{
Options opt;
opt.setSigmaRoughness(2. * Units::angstrom);
opt.setTransientModel(new TanhTransient);
auto sample = FeNiBilayer{std::move(opt)};
return sample.release();
}
Sample* ExemplarySamples::createFeNiBilayerNC()
{
Options opt;
opt.setSigmaRoughness(2. * Units::angstrom);
opt.setTransientModel(new ErfTransient);
auto sample = FeNiBilayer{std::move(opt)};
return sample.release();
}
Sample* ExemplarySamples::createFeNiBilayerSpinFlip()
{
Options opt;
opt.setAngle(38. * deg);
auto sample = FeNiBilayer{std::move(opt)};
return sample.release();
}
Sample* ExemplarySamples::createFeNiBilayerSpinFlipTanh()
{
Options opt;
opt.setAngle(38. * deg);
opt.setSigmaRoughness(2. * Units::angstrom);
opt.setTransientModel(new TanhTransient);
auto sample = FeNiBilayer{std::move(opt)};
return sample.release();
}
Sample* ExemplarySamples::createFeNiBilayerSpinFlipNC()
{
Options opt;
opt.setAngle(38. * deg);
opt.setSigmaRoughness(2. * Units::angstrom);
opt.setTransientModel(new ErfTransient);
auto sample = FeNiBilayer{std::move(opt)};
return sample.release();
}
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