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Low Temperature Phase of the m-component Spin Glass / Die Tieftemperaturphase des m-Komponenten SpinglasesBraun, Axel 29 June 2011 (has links)
No description available.
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Physics of laser heated ferromagnets: Ultrafast demagnetization and magneto-Seebeck effect / Physik lasergeheizter Ferromagnete: Ultraschnelle Entmagnetisierung und magneto-Seebeck EffektWalowski, Jakob 05 March 2000 (has links)
No description available.
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Untersuchung der elektrischen Phasenseparation in dünnen Manganatschichten mit Rastersondenspektroskopie / Intrinsic phase separation in manganite thin films investigated with scanning tunneling spectroscopyBecker, Thomas 08 June 2004 (has links)
No description available.
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Structural and Magnetic Properties of the Glass-Forming Alloy Nd60Fe30Al10 / Mikrostrukturelle und magnetische Eigenschaften der glasbildenden Legierung Nd60Fe30Al10Bracchi, Alberto 18 November 2004 (has links)
No description available.
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Epitaktisches Wachstum und Charakterisierung ultradünner Eisenoxidschichten auf Magnesiumoxid(001)Zimmermann, Bernd Josef 17 September 2010 (has links)
Since many years, the importance of thin layers increases for lots of
technical uses. Beginning in the field of microelectronics, the use of thin
layers spread increasingly to other areas. Coatings for surface refining and
optimisation of the mechanical properties for material engineering,
customisation of the surface chemistry in catalysts, as well influencing of
the transmission and reflection characteristics of surfaces in optics are
only some examples of the high scientific and economic weight of the thin
layer technology. Thin magnetic layers are the basis of many known
storage media ranging from the tape recorder to the hard disk up to the
credit card. Nowadays, these thin layers again gain interest in the research
field of nanoelectronics as ultrathin layers. So-called spinvalve-read/write
heads being already installed in actual hard disks use the Tunnel Magneto
Resistance effect for a significant rise in memory density synonymous
capacity. Such read/writeheads consist of a magnetic layersystem. This
use of the magnetic as well as the electric characteristics of the electrons
is called spintronics. The iron oxide magnetite exhibits a high iron portion,
is strong antiferrimagnetic and has a high Curie-temperature. Since many
years, it is used as a magnetic pigment on already mentioned magnetic
tapes. Literature [1, 2, 3, 4] considers ultrathin epitaxial layers of magnetite
on magnesium oxide for uses in the spintronics as a most promising
candidate, because it inheres a complete spin polarisation at Fermi-level.
Moreover, thin magnetite layers serve in the chemical industry as a catalyst
in the Haber- Bosch-procedure and to the dehydration of ethylbenzene to
styrene. Being already used and considered to be of ongoing interest,
ultrathin magnetite layers offer a wide range of technological applications in
many modern industrial and scientific fields. Because there is,
nevertheless, a variety of other iron oxide (cf. chapter 4), it is a matter to
determine the special growth conditions of magnetite. These ultrathin iron
oxide layers were grown reactively on the (001)-surfaces of the magnesium
oxide substrate by molecular beam epitaxy. Besides, the surface is
examined by the diffraction of low-energy electrons concerning its
crystalline structure. X-ray photo electron spectroscopy approaching the
stochiometry completes these first characterisations. Other investigations
are carried out at HASYLAB / DESY in Hamburg by X-ray reflectivity and X-ray
diffraction. The exact thickness of the layers, its crystal properties in bulk, as
well as the thickness of the crystalline portion of the layers can be
determined among other features of the system. The evaluation of XRR-and XRD-investigations is done via simulations with in chapter 5
introduced software packages. The reader finds the theoretical
backgrounds to the used techniques in chapter 3. The experimental setups
in Osnabr¨uck and Hamburg as well as the backgrounds to the
preparation are presented in chapter 5. Because the formation of the
different iron oxides is described in literature [5, 6, 7, 8] as mostly
depending on annealing temperatures, the experimental results in chapter
6 are graded accordingly. The dependence on temperature, layer thickness
and annealing time should be examined for the iron oxides possible on
this substrate. The aim of this work is the preparation of ultrathin epitaxial
iron oxide layers with thicknesses up to few nanometers. The main goal is
to find the growth parameters for ultrathin crystalline magnetite
layers.
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Thermische Stabilität und Reaktion metallischer Multilagen / Thermal stability and reaction of metallic multilayersEne, Constantin Buzau 19 December 2007 (has links)
No description available.
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Structural and magnetic properties of ultrathin Fe3O4 films: cation- and lattice-site-selective studies by synchrotron radiation-based techniquesPohlmann, Tobias 19 August 2021 (has links)
This work investigates the growth dynamic of the reactive molecular beam epitaxy of Fe3O4 films, and its impact on the cation distribution as well as on the magnetic and structural properties at the surface and the interfaces. In order to study the structure and composition of Fe3O4 films during growth, time-resolved high-energy x-ray diffraction (tr-HEXRD) and time-resolved hard x-ray photoelectron spectroscopy (tr-HAXPES) measurements are used to monitor the deposition process of Fe3O4 ultrathin films on SrTiO3(001), MgO(001) and NiO/MgO(001). For Fe3O4\SrTiO3(001) is found that the film first grows in a disordered island structure, between thicknesses of 1.5nm to 3nm in FeO islands and finally in the inverse spinel structure of Fe3O4, displaying (111) nanofacets on the surface. The films on MgO(001) and NiO/MgO(001) show a similar result, with the exception that the films are not disordered in the early growth stage, but form islands which immediately exhibit a crystalline FeO phase up to a thickness of 1nm. After that, the films grown in the inverse spinel structure on both MgO(001) and NiO/MgO(001). Additionally, the tr-HAXPES measurements of Fe3O4/SrTiO3(001) demonstrate that the FeO phase is only stable during the deposition process, but turns into a Fe3O4 phase when the deposition is interrupted. This suggests that this FeO layer is a strictly dynamic property of the growth process, and might not be retained in the as-grown films. In order to characterize the as-grown films, a technique is introduced to extract the cation depth distribution of Fe3O4 films from magnetooptical depth profiles obtained by fitting x-ray resonant magnetic reflectivity (XRMR) curves. To this end, x-ray absorption (XAS) and x-ray magnetic circular dichroism (XMCD) spectra are recorded as well as XRMR curves to obtain magnetooptical depth profiles. To attribute these magnetooptical depth profiles to the depth distribution of the cations, multiplet calculations are fitted to the XMCD data. From these calculations, the cation contributions at the three resonant energies of the XMCD spectrum can be evaluated. Recording XRMR curves at those energies allows to resolve the magnetooptical depth profiles of the three iron cation species in Fe3O4. This technique is used to resolve the cation stoichiometry at the surface of Fe3O4/MgO(001) films and at the interfaces of Fe3O4/MgO(001) and Fe3O4/NiO. The first unit cell of the Fe3O4(001) surface shows an excess of Fe3+ cations, likely related to a subsurface cation-vacancy reconstruction of the Fe3O4(001) surface, but the magnetic order of the different cation species appears to be not disturbed in this reconstructed layer. Beyond this layer, the magnetic order of all three iron cation species in Fe3O4/MgO(001) is stable for the entire film with no interlayer or magnetic dead layer at the interface. For Fe3O4/NiO films, we unexpectedly observe a magnetooptical absorption at the Ni L3 edge in the NiO film corresponding to a ferromagnetic order throughout the entire NiO film, which is antiferromagnetic in the bulk. Additionally, the magnetooptical profiles indicate a single intermixed layer containing both Fe2+ and Ni2+ cations.
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Short range ordering and microstructure property relationship in amorphous alloys / Nahordnung und Mikrostruktur-Eigenschaftsbeziehungen in amorphen LegierungenShariq, Ahmed 09 January 2007 (has links)
No description available.
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