Восстановление комплексного коэффициента отражения по алгоритму опорного слоя для многослойных систем с неколлинеарным магнитным упорядочением

Yuri A. Salamatov; Ekaterina S. Nikova; Denis I. Devyaterikov; Evgeny A. Kravtsov

doi:10.21638/11701/spbu10.2022.412

Authors

Yuri A. Salamatov M. N. Mikheev lnstitute of Metal Physics of Ural Branch of Russian Academy of Sciences, 18, ul. Sofii Kovalevskoy, Ekaterinburg, 620137, Russian Federation https://orcid.org/0000-0002-3857-2392
Ekaterina S. Nikova M. N. Mikheev lnstitute of Metal Physics of Ural Branch of Russian Academy of Sciences, 18, ul. Sofii Kovalevskoy, Ekaterinburg, 620137, Russian Federation https://orcid.org/0000-0002-4142-3072
Denis I. Devyaterikov M. N. Mikheev lnstitute of Metal Physics of Ural Branch of Russian Academy of Sciences, 18, ul. Sofii Kovalevskoy, Ekaterinburg, 620137, Russian Federation
Evgeny A. Kravtsov M. N. Mikheev lnstitute of Metal Physics of Ural Branch of Russian Academy of Sciences, 18, ul. Sofii Kovalevskoy, Ekaterinburg, 620137, Russian Federation

DOI:

https://doi.org/10.21638/11701/spbu10.2022.412

Abstract

This work analyzes two mathematical algorithms for processing experimental curves in polarized neutron reflectometry, one of which makes it possible to determine the complex reflection coefficient. The approbation was carried out for a Fe/Cr type superlattice with an irregular non-collinear ordering of the magnetic moments of the Fe layers. The processing of the experiment was carried out both by direct refinement of the structure parameters and by the method of calculating the module and phase of the reflectometry signal using the Gd reference layer. The results obtained with different methods are compared with each other. To clarify the structural and magnetic characteristics, the Levenberg-Marquardt algorithm was applied in both cases. The obtained data on the magnetic structure is in agreement with the theoretical model of magnetization of a layered antiferromagnet of finite dimensions in a weak field. The presented modification of the reference layer method can be considered as the phase problem solution in polarized neutron reflectometry.

Keywords:

polarized neutron reflectometry, phase-amplitude function method, Runge-Kutta method, complex reflection coefficient, multilayer nanoheterostructures, phase problem, non-collinear magnetic ordering, reference layer, Levenberg-Marquardt algorithm

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References

Литература

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Nikova E. S., Salamatov Yu. A., Kravtsov E. A., Ustinov V. V. Application of a Gd reference layer for the study of magnetic metallic nanostructures by neutron reflectometry // Journal of Surface Investigation. X-ray, Synchrotron and Neutron Techniques. 2021. Vol.15. N5. P.899-902.

References

Baibich M. N., Broto J. M., Fert A., Nguyen Van Dau F., Petroff F., Etienne P., Creuzet G., Friederich A., Chazelas J. Giant magnetoresistance of (001)Fe/(001)Cr magnetic superlattices. Physical Review Letters, 1988, vol.61, iss.21, pp.2472-2475.

Binasch G., Grunberg P., Saurenbach F., Zinn W. Enhanced magnetoresistance in layered magnetic structures with antiferromagnetic interlayer exchange. Physical Review B, 1989, vol.39, iss.7, pp.4828-4830.

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Ustinov V. V. Spin-flop transition scenario in finite layered antiferromagnets. Journal of Magnetism and Magnetic Materials, 2007, vol.310, iss.2, pp.2219-2221.

Lauter-Pasyuk V., Lauter H., Toperverg B., Romashev L., Ustinov V. Transverse and lateral structure of the spin-flop phase in Fe/Cr antiferromagnetic superlattices. Physical Review Letters, 2002, vol.89, iss.16, p.167203.

Babikov V. V. Metod fazovyh funkcij v kvantovoj mekhanike [Phase function method in quantum mechanics]. Moscow, Nauka Publ., 1976, 288p. (In Russian)

Lekner J. Theory of reflection of electromagnetic and particle waves. Dordrecht, Springer Science+Business Media Publ., 1987, 281p.

Zimmerman K. M. Advanced analysis techniques for X-ray reflectivities: theory and application. Doctoral dissertation in chemistry. Karlsruhe, University of Dortmund Press, 2005, 190p.

De Haan V. O., van Well A. A., Sacks P. E., Adenwalla S., Felcher G. P. Toward the solution of the inverse problem in neutron reflectometry. Physica B: Physics of Condensed Matter, 1996, vol.221, iss.1-4, pp.524-532.

Lynn J. E., Seeger P. A. Resonance effects in neutron scattering lengths of rare-earth nuclides. Atomic Data and Nuclear Data Tables, 1990, vol.44, iss.2, pp.191-207.

Nikova E. S., Salamatov Yu. A., Kravtsov E. A., Bodnarchuk V. I., Ustinov V. V. Experimental determination of gadolinium scattering characteristics in neutron reflectometry with reference layer. Physica B: Physics of Condensed Matter, 2019, vol.552, pp.58-61.

Aksenov V. L., Lauter-Pasyuk V. V., Lauter H., Nikitenko Yu. V., Petrenko A.V. Polarized neutrons at pulsed sources in Dubna. Physica B: Physics of Condensed Matter, 1996, vol.335, iss.1-4, pp.147-152.

Nikova E. S., Salamatov Yu. A., Kravtsov E. A., Ustinov V.V. Application of a Gd reference layer for the study of magnetic metallic nanostructures by neutron reflectometry. Journal of Surface Investigation. X-ray, Synchrotron and Neutron Techniques, 2021, vol.15, no.5, pp. 899-902.