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Theses

Précession de l'aimantation par transfert de spin dans des nanopiliers magnétiques

Abstract : This thesis is dedicated to the experimental study of the dynamics of magnetization induced by spin transfer in magnetic nanopillars. The recent discovery that a spin polarized current can exert a torque on the magnetization of a ferromagnetic body, via transfer of spin momentum, opens a new way to manipulate magnetization with no applied field. This "spin transfer torque" can, for a high enough current, switch magnetization or even in some cases generate steady precession state of magnetization associated with microwave generation.
In this thesis, spin transfer effects were studied in specific Co/Cu/Ni80Fe20 magnetic structures in which an oscillatory angular dependence of the torque (called "wavy" ) is predicted by the diffusive spin transfer models. This "wavy" torque deeply modifies the dynamics of magnetization induced by the spin transfer torque and allows precession states of magnetization with no applied field, only by injecting a DC current in the structure. The static transport characterizations and high frequency measurements on this magnetic nanopillars with a wavy torque clearly show new kinds of steady precession modes at zero (or low) field, in agreement with the predictions of the theoretical models and the dynamical simulations. This thesis work is a successful test of diffusive models of spin transfer and opens the way to a new type of spin transfer oscillators that do not need an applied field.
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Contributor : Olivier Boulle <>
Submitted on : Thursday, April 10, 2008 - 7:17:32 PM
Last modification on : Wednesday, December 9, 2020 - 3:16:23 PM
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  • HAL Id : tel-00175478, version 4

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Olivier Boulle. Précession de l'aimantation par transfert de spin dans des nanopiliers magnétiques. Matière Condensée [cond-mat]. Université Pierre et Marie Curie - Paris VI, 2007. Français. ⟨tel-00175478v4⟩

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