Dépiégeage de parois magnétiques par activation thermique et transfert de spin dans des nanostructures d'alliage FePt

Andrei Mihai 1
1 NM - Nanostructures et Magnétisme
SP2M - UMR 9002 - Service de Physique des Matériaux et Microstructures : DSM/INAC/SP2M
Abstract : We studied the magnetization reversal in FePt/MgO thin layers and FePt/Pt/FePt/MgO spin-valves with perpendicular magnetization deposited by molecular beam epitaxy at high temperature. These structures have been characterized and their magnetical and electrical properties have been optimized. The contribution to the resistivity of the electron-magnon scattering (Magnon Magneto Resistance (MMR)) has been studied in detail in FePt/MgO layers. Theoretical analysis of this effect has been given, relating the linear dependence of the MMR on the field with the strong anisotropy of the FePt layer. We show that the MMR, which increases with the temperature, provides a new detection technique for magnetization switching. We investigated the influence of an applied direct current on the propagation of a magnetic domain wall (DW) through FePt based nanostructures. Extraordinary Hall Effect (EHE) and GMR measurements were performed on highly anisotropic FePt films and FePt/Pt/FePt spinvalves, nano-structured into wires. These systems allow the study of the thermally activated depinning of a magnetic DW from a single instrinsic structural defect. In both cases, the pinning time is found to be stochastic. Finally, we show that a low applied direct current can strongly modify the mean pinning time thus demonstrating the high efficiency of the spin-transfer mechanism in FePt.
Mots-clés : magnetisme spintronique
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Submitted on : Wednesday, December 12, 2012 - 5:04:34 PM
Last modification on : Thursday, March 7, 2019 - 5:00:03 PM
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Andrei Mihai. Dépiégeage de parois magnétiques par activation thermique et transfert de spin dans des nanostructures d'alliage FePt. Science des matériaux [cond-mat.mtrl-sci]. Université Joseph-Fourier - Grenoble I, 2009. Français. ⟨tel-00764316⟩

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