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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Neutron scattering studies of transition metal alloys

Lindley, E. J. January 1985 (has links)
No description available.
2

Modeling Inter-Particle Magnetic Correlations in Magnetite Nanoparticle Assemblies Using X-ray Magnetic Scattering Data

Rackham, Johnathon Michael 07 June 2022 (has links)
Magnetic nanoparticles are used in nanotechnologies and biomedical applications, such as drug targeting, hyperthermia, MRI contrasting agents, and bio-separation of compound solutions. Magnetite (Fe3O4) nanoparticles stand to be effective in these roles due to the non-toxic nature of magnetite and its ease of manufacture. To this end, a greater understanding of the magnetic behavior of the individual magnetite nanoparticles is needed when a collection of them is used. This research seeks to discover the local magnetic ordering of ensembles of magnetite nanoparticles at various stages of the magnetization process, temperatures above and below their blocking temperature, and for various particle sizes. We use x-ray circular dichroism and x-ray resonant magnetic scattering (XRMS), which provides information about the magnetic orders in the samples. Here we discuss the modeling of the magnetic scattering data using a one-dimensional chain of nanoparticles in real space as well as an empirical Gaussian packet model in reciprocal space. We find that at low temperature, and field values close to the coercive point, magnetite nanoparticles experience a significant amount of antiferromagnetic ordering that increases with particle size.
3

P-type thermoelectric materials for waste heat recovery system: P-type Mg<sub>2</sub>Sn<sub>1-x</sub>Si<sub>x</sub> and Pb<sub>1-x-y</sub>Eu<sub>x</sub>Se:Na<sub>y</sub>

Kim, Sunphil 10 October 2014 (has links)
No description available.
4

MAGNETO-OPTICAL PROPERTIES OF THIN PERMALLOY FILMS: A STUDY OF THE MAGNETO-OPTICAL GENERATION OF LIGHT CARRYING ANGULAR MOMENTUM

Montgomery, Patrick D. 01 January 2018 (has links)
Magneto-optical materials such as permalloy can be used to create artificial spin- ice (ASI) lattices with antiferromagnetic ordering. Magneto-optical materials used to create diffraction lattices are known to exhibit magnetic scattering at the half- order Bragg peak while in the ground state. The significant drawbacks of studying the magneto-optical generation of OAM using x-rays are cost, time, and access to proper equipment. In this work, it is shown that the possibility of studying OAM and magneto-optical materials in the spectrum of visible light at or around 2 eV is viable. Using spectroscopic ellipsometry it is possible to detect a change in the magnetization of thin permalloy films with thicknesses between 5 and 20 nm. Patterns consistent with OAM were found at 1.95 eV using a square lattice with a 4𝜋 radial phase shift in the antiferromagnetic ground state. Evidence of magnetic scattering at the half-order Bragg peak using 1.95 eV was also found.
5

Ultrafast modification of the magnetic anisotropy in a CoTb alloy / Modification ultrarapide de l'anisotropie magnétique dans un alliage CoTb

Merhe, Alaa el dine 13 November 2018 (has links)
Dans cette thèse, nous rapportons l'évolution temporelle du premier et du troisième ordre de la diffusion magnétique d'un film CoTb amorphe après une excitation femtoseconde. Ces résultats sont obtenus en appliquant une diffusion résonnants de rayons X aux petits angles au seuil d'absorption magnétique de Co M3 via des expériences de pompe sonde répétitives. Une différence de comportement entre le premier et le troisième ordre de diffusion a été observée après 3,5 ps, où une seconde baisse de l'intensité du troisième ordre apparaît. En utilisant des modèles appropriés, nous montrons que cette différence est due à une augmentation de la largeur de la paroi du domaine séparant deux domaines opposés. Nous supposons que cet élargissement de la paroi est généré par une variation de l'anisotropie uniaxiale hors plan due au réchauffement thermique du réseau par l'impulsion laser femtoseconde. Cette interprétation est vérifiée en mesurant l’anisotropie uniaxiale en fonction de la température de chauffage en effectuant des mesures statiques SQUID-VSM. / In this thesis, we report the time evolution of first and third order of magnetic scattering from an amorphous CoTb film after a femtosecond excitation. These results are obtained by applying a resonant small angle X ray scattering at the Co magnetic absorption edge M3 via a repetitive pump probe experiments. Difference in behaviours between the first and third scattering orders was observed after 3.5 ps where a second drop of the third order intensity appears. Using suitable models, we show that this difference is due to an increase of the domain wall width separating two opposite domains. We suppose that this wall broadening is generated by the variation of the out of plane uniaxial anisotropy due to the thermal heating of the lattice by the femtosecond laser pulse. This interpretation is verified by following the uniaxial anisotropy as function of the heating temperature by doing static SQUID-VSM measurements
6

Rozptylové ztráty v magnetických materiálech na konci statorového svazku / Stray losses in magnetic material in the end of stator packet

Kopecký, Ivo January 2010 (has links)
This thesis examines the magnetic field and magnetic flow at the end of the stator synchronous machine. This problem is solid using nonlinear magnetic resistive network, which is simulating by PSpice software. A simple model of stator, consisting of stator plates, air gaps and the two-thumbs, which hold the stator together. All of this is replace magnetic nonlinear resistive network, which is then divided into elements. According to these element is a simplified model solid and analyzed.

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