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Correlation of structural, chemical and magnetic properties in annealed Ti/Ni multilayer structures
Inter-University Consortium for DAE Facilities.
Inter-University Consortium for DAE Facilities, Indore, India.
Inter-University Consortium for DAE Facilities, Indore, India.
2005 (English)In: Journal of Applied Physics, ISSN 0021-8979 (print), 1089-7550 (online), Vol. 97, no 4, 043509- p.Article in journal (Refereed) Published
Abstract [en]

Ti/Ni multilayer samples have been synthesized on float glass substrates using an electron-beam evaporation technique under ultrahigh vacuum conditions at room temperature. Grazing incidence x-ray diffraction (GIXRD) and grazing incidence x-ray reflectivity (GIXRR) techniques were used, respectively, to study structural modifications and to determine corresponding changes in microstructural parameters, such as individual layer thickness, interface roughness, and electron density due to annealing treatment. In addition to this, the chemical nature of the surface and interfaces of these samples were also studied using a depth profile x-ray photoelectron spectroscopy (XPS) technique. The GIXRD measurement show clear amorphization of the as-deposited multilayer sample annealed in the temperature range of 300–400 °C. The corresponding GIXRR measurement indicates the formation of a sufficiently thick layer of Ti–Ni at interfaces converting the Ti/Ni bilayer into a Ti/Ti–Ni/Ni trilayer multilayer structure. The precipitation of the Ti–Ni alloy phase at the interface in the case of samples annealed at 400 °C has been confirmed by XPS measurements. The magnetization behavior investigated using the magneto-optical Kerr effect technique clearly shows well the saturation magnetization behavior for all samples annealed up to 300 °C, while the sample annealed at 400 °C does not show saturation magnetization. The corresponding coercivity value (Hc) is also found to be changed drastically from 15.5 to 0.6 Oe. This observed magnetization behavior is discussed and correlated with structural and chemical changes in the multilayer structure.

Place, publisher, year, edition, pages
2005. Vol. 97, no 4, 043509- p.
Keyword [en]
titanium alloys, nickel alloys, ferromagnetic materials, magnetic multilayers, electron beam deposition, vacuum deposition, annealing, amorphisation, interface roughness, electron density, Kerr magneto-optical effect, coercive force, magnetic hysteresis, X-ray diffraction, X-ray photoelectron spectra, titanium, nickel
National Category
Natural Sciences
URN: urn:nbn:se:liu:diva-13113DOI: 10.1063/1.1835561OAI: diva2:17860
Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2010-06-14
In thesis
1. Fabrication and study of inorganic and organic thin film magnets
Open this publication in new window or tab >>Fabrication and study of inorganic and organic thin film magnets
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Thin film magnets are very important for many kinds of electronic devices and play a crucial role to achieve optimum performance. Therefore an intense level of research is going on all around the world to fabricate advanced electronics devices using both new inorganic and organic thin-film magnets. Historically, most magnetic materials used for technological applications are based on inorganic materials and have been studied extensible up to now. Recently, however, organic or molecular magnets have opened a new prospective of thin film magnets which have begun to show promise, offering the possibility of light-weight flexible materials and devices that include magnetic functionality.

The research presented in this thesis is hence divided into two parts, where inorganic and organic magnets in thin films form were studied. The Ti/Ni multilayer system is studied as an inorganic magnet in the first part, whereas M(TCNE)x thin films were studied in the second part with M= Fe, Ni and TCNE is tetracynoethelene, an organic compound, and x~2.

The Ti/Ni multilayer is a potential candidate for industrial applications and also features solid-state amorphisation. Because of various interesting scientific and technological aspects of Ti/Ni multilayer structures, many structural properties and subsequent thermal stability studies have been extensively reported in the literature, but surprisingly few reports are available on the corresponding electronic and magnetic properties. The work in the present thesis is therefore focused on synthesis and systematic investigation of structural, electronic and magnetic properties of as prepared as well as annealed Ti/Ni multilayer structures and to establish correlation between them.

The second part of the thesis deals with organic-based molecular magnets of the M(TCNE)x type, where x~2, M = Fe, Ni and TCNE = tetracynoethelene. Fe(TCNE)x and Ni(TCNE)x have for the first time been fabricated as thin films, free of oxygen- and precursor-induced defects. The films were fabricated in situ under ultra high vacuum conditions using our group’s recently developed fabrication techniques for organic-based molecular magnets. The previously unknown electronic structure of these thin film magnets are presented in the thesis. Room temperature magnetic ordering was observed for thin films of Ni(TCNE)2, in stark contrast to earlier versions of the material (fabricated with the old methods and hence containing various defects). Room temperature magnetic ordering for a similar system, Ni2(TCNE), previously has been reported by another group, but it is clear that more studies are necessary to completely resolve the underlying mechanisms for the magnetic properties seen in these materials.

Place, publisher, year, edition, pages
Linköping: Institutionen för teknik och naturvetenskap, 2007. 65 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1152
Physics, electronic, thin films, inorganic magnets, organic magnets
National Category
Physical Sciences
urn:nbn:se:liu:diva-11442 (URN)978-91-85895-20-5 (ISBN)
Public defence
2007-12-14, K3, Kåkenhus, Campus Norrköping, Linköpings universitet, Norrköping, 10:15 (English)
Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2012-11-21

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Bhatt, Pramod
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