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Magnetic Properties...
Magnetic Properties of Epitaxial Metal/Oxide Heterostructures
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- Warnatz, Tobias (author)
- Uppsala universitet,Materialfysik
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- Hjörvarsson, Björgvin (thesis advisor)
- Uppsala universitet,Materialfysik
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- Magnus, Fridrik (thesis advisor)
- University of Iceland, Science Institute
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- Kapaklis, Vassilios, 1978- (thesis advisor)
- Uppsala universitet,Materialfysik
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- Parkin, Stuart S.P. (opponent)
- Martin-Luther-University Halle-Wittenberg, Institute of Physics
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(creator_code:org_t)
- ISBN 9789151312217
- Uppsala : Acta Universitatis Upsaliensis, 2021
- English 64 s.
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Series: Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1651-6214 ; 2049
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Abstract
Subject headings
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- The work in this dissertation is devoted to tailoring and studying magnetic properties of epitaxial metal/oxide heterostructures. The aim is to understand the fundamental principles governing these properties and how they affect each other. The acquired knowledge can prove useful for the development of future spintronic devices. A variety of experimental techniques is used to fabricate and characterize the epitaxial structures. For fabrication, a combination of direct-current and radio-frequency sputtering is used, whereas x-ray reflectivity and diffraction measurements are the main tools for the structural characterization of the heterostructures. The magnetic characterization of these structures is done by a combination of longitudinal magneto-optical Kerr-effect measurements, Kerr-microscopy and polarized neutron reflectometry. First, it is shown how strain affects the magnetic properties of metal/oxide heterostructures by comparing Fe/MgO and Fe/MgAl2O4 superlattices. Subsequently, an antiferromagnetic interlayer exchange coupling in Fe/MgO superlattices is revealed and attributed to a spin-polarized-tunneling mechanism. The coupling strength can be tuned by changing the MgO thickness leading to the stabilization of different remanent states as well as to different reversal mechanisms. It is shown that the interlayer exchange coupling in Fe/MgO superlattices is a consequence of two distinct components. These components can be interpreted as beyond-nearest-neighbor interactions and a contribution arising from the total thickness of the heterostructures.The interlayer exchange coupling is further investigated via temperature dependent magnetization measurements. It is shown that different remanent states and reversal mechanisms occur at different temperatures. Furthermore, a large increase in interlayer exchange coupling strength with reduced temperature is revealed. Finally, it is shown that Fe84Cu16/MgO superlattices exhibit a reduced magnetocrystalline anisotropy and interlayer exchange coupling strength, as compared to pure Fe/MgO superlattices. Patterning such Fe84Cu16/MgO superlattices in circular islands leads to an increased saturation field with decreasing island diameter.
Subject headings
- NATURVETENSKAP -- Fysik -- Den kondenserade materiens fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Condensed Matter Physics (hsv//eng)
Keyword
- Fe/MgO
- interlayer exchange coupling
- anisotropy
- IEC
- superlattice
- multilayer
- polarized neutron reflectometry
- PNR
- Physics with spec. in Atomic, Molecular and Condensed Matter Physics
- Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik
Publication and Content Type
- vet (subject category)
- dok (subject category)
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