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Theses

Jonctions tunnel à aimantation perpendiculaire :
- Croissance, caractérisations structurales
- Phénomènes de couplage, magnétotransport
- Extension aux hétérostructures pour l'injection de spins dans les semiconducteurs III-V

Abstract : This thesis aimed at the elaboration by epitaxy and the characterization of devices designed for spintronic applications: magnetic tunnel junctions (FePt/MgO/FePt) and hybrid heterostructures ferromagnetic metal / semiconductor III-V (FePt/MgO/GaAs). In both cases we used MgO as an insulating barrier and FePt ferromagnetic electrodes with magnetization perpendicular to the surface plane (the L10 ordered alloy). This ferromagnetic material has been chosen for the purpose of creating future magnetic memories because its large anisotropy enables a stable magnetic information.
Different magnetic behaviors have been shown for each of the two electrodes of the magnetic tunnel junctions. Structural characterizations of the system performed during the growth process led us to attribute this effect to the epitaxial strain of the thin films. Surprisingly at first sight, the magnetic decoupling of the system is not guaranteed in the general case because of the strong magnetization of the ferromagnetic layers that induces a strong stray field during the magnetization reversals. We also were able to deduce, by experiments and calculations, the influence of the thickness of the electrodes on the general magnetic properties of the device. Studies of magnetization reversal dynamics have shed some light on the key role played by the pinning of the domain walls during the magnetization reversals.
All-epitaxial FePt/MgO/GaAs hybrid systems were elaborated by combining different deposition chambers. We managed to grow systems exhibiting the desired structural and magnetic properties.
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https://tel.archives-ouvertes.fr/tel-00151284
Contributor : Pierre de Person <>
Submitted on : Tuesday, August 14, 2007 - 10:19:07 PM
Last modification on : Wednesday, November 4, 2020 - 2:45:51 PM
Long-term archiving on: : Friday, November 25, 2016 - 6:57:45 PM

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  • HAL Id : tel-00151284, version 2

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Pierre de Person. Jonctions tunnel à aimantation perpendiculaire :
- Croissance, caractérisations structurales
- Phénomènes de couplage, magnétotransport
- Extension aux hétérostructures pour l'injection de spins dans les semiconducteurs III-V. Matière Condensée [cond-mat]. Université Joseph-Fourier - Grenoble I, 2007. Français. ⟨tel-00151284v2⟩

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