Skip to Main content Skip to Navigation
Theses

Magnétorésistance de magnon reversement de l'aimantation et dynamique de parois dans FePt et NiFe nanostructures

Abstract : In the first part of this thesis, we study the magnetization reversal process of FePt nanowires with high magnetocrystalline anisotropy. When reducing the wire width below the mean dendrite width, the magnetization reversal favors a transition from the dendrite growth to the propagation of a single domain wall (DW). Further decreasing of the width towards the disorder length and/or the mean edge roughness leads to a large increase of coercivity, which finally results in a mix of DW propagation and nucleation in ultra-narrow wires. The second part focuses on the use of Magnon magnetoresistance (MMR), i.e., the magnon contribution to the resistivity, to study the magnetization reversal in nanostructures with either perpendicular (FePt) or planar magnetization (NiFe). We showed that MMR can be used in nanowires and nanomagnets, in particular to detect DW position in nanowires processed in a single layer. Finally, the dynamic of DW depinning under field and current in both FePt and NiFe systems has been studied. We observe three different modes of DW depinning, which depend on the nature of defects, or on the geometry of the constriction. Statistical analysis of the pinning time indeed shows that the depinning path can be described as simple path, serial paths or alternative paths. Additionally, the effect of DC current on all depinning mechanisms is found to be equivalent to the effect of applied field which, allow measuring the spin transfer efficiency in these systems.
Complete list of metadata

Cited literature [160 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-00772893
Contributor : Abes Star :  Contact
Submitted on : Friday, January 11, 2013 - 12:07:40 PM
Last modification on : Wednesday, November 4, 2020 - 2:35:25 PM
Long-term archiving on: : Saturday, April 1, 2017 - 4:02:01 AM

File

33408_NGUYEN_2012_archivage1.p...
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-00772893, version 1

Collections

Citation

van Dai Nguyen. Magnétorésistance de magnon reversement de l'aimantation et dynamique de parois dans FePt et NiFe nanostructures. Autre [cond-mat.other]. Université de Grenoble, 2012. Français. ⟨NNT : 2012GRENY039⟩. ⟨tel-00772893⟩

Share

Metrics

Record views

519

Files downloads

261