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Study of magnetoelastic coupling in multiferroic heterostructures

Piotr Graczyk

Abstract

This work contains of three aims. First, the influence of spontaneous strain of bulk ferroelastic crystal onto magnetization of ferromagnetic thin film is showed experimentally by SQUID magnetometry. I showed a significant change in a thin NiFe film magnetization as a consequence of magnetoelastic coupling with a ferroelastic LiCsSO4 and KH2PO4 substrate. The results that are quantitatively consistent with the experimental data were obtained assuming the micromagnetic model. The magnetic domains in the NiFe were found by Kerr microscopy to strictly mimic the pattern of ferroelastic domains. This effect was quantitatively described in terms of a Stoner-Wohlfarth model, which permitted an estimation of the magnetostriction constant and the evolution of the magnetic easy axis in the film. Secondly, it is showed that Gd2(MoO4)3 substrate changed the frequency of magnetostatic surface spin wave in NiFe thin film. I compared the experimental values of this change with theoretical predictions using micromagnetic calculations and dispersion relations for spin waves. Such ferroelastic - ferromagnetic structure can be applied in the future, for example, to electrically tune the frequency of a spin wave, what may be useful in rapidly developing magnonic technology. For this purpose it is necessary to obtain high quality thin films of gadolinium molybdate, which was the last goal of this work. GMO thin films were deposited onto different substrates by pulsed laser deposition technique. High-quality, epitaxial α’-Gd2(MoO4)3 films of tetragonal defect scheelite type structure were obtained.
Record ID
UAMae8273a2f7f34bda9efb637b2dd5863c
Diploma type
Doctor of Philosophy
Author
Piotr Graczyk (SNŚ/WyF/DoNP) Piotr Graczyk,,
Title in Polish
Badanie sprzężeń magnetosprężystych w multiferroikach heterostrukturalnych
Title in English
Study of magnetoelastic coupling in multiferroic heterostructures
Language
pl Polish
Certifying Unit
Faculty of Physics (SNŚ/WyF/FoP)
Discipline
physics / (physical sciences domain) / (physical sciences)
Scientific discipline (2.0)
6.6 physical sciences
Defense Date
06-09-2016
End date
06-09-2016
Supervisor
URL
http://hdl.handle.net/10593/14888 opening in a new tab
Keywords in English
multiferroics, thin films, magnetostriction, magnetism
Abstract in English
This work contains of three aims. First, the influence of spontaneous strain of bulk ferroelastic crystal onto magnetization of ferromagnetic thin film is showed experimentally by SQUID magnetometry. I showed a significant change in a thin NiFe film magnetization as a consequence of magnetoelastic coupling with a ferroelastic LiCsSO4 and KH2PO4 substrate. The results that are quantitatively consistent with the experimental data were obtained assuming the micromagnetic model. The magnetic domains in the NiFe were found by Kerr microscopy to strictly mimic the pattern of ferroelastic domains. This effect was quantitatively described in terms of a Stoner-Wohlfarth model, which permitted an estimation of the magnetostriction constant and the evolution of the magnetic easy axis in the film. Secondly, it is showed that Gd2(MoO4)3 substrate changed the frequency of magnetostatic surface spin wave in NiFe thin film. I compared the experimental values of this change with theoretical predictions using micromagnetic calculations and dispersion relations for spin waves. Such ferroelastic - ferromagnetic structure can be applied in the future, for example, to electrically tune the frequency of a spin wave, what may be useful in rapidly developing magnonic technology. For this purpose it is necessary to obtain high quality thin films of gadolinium molybdate, which was the last goal of this work. GMO thin films were deposited onto different substrates by pulsed laser deposition technique. High-quality, epitaxial α’-Gd2(MoO4)3 films of tetragonal defect scheelite type structure were obtained.
Thesis file

Uniform Resource Identifier
https://researchportal.amu.edu.pl/info/phd/UAMae8273a2f7f34bda9efb637b2dd5863c/

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