Jonctions tunnel magnétiques à aimantation perpendiculaire : anisotropie, magnétorésistance, couplages magnétiques et renversement par couple de transfert de spin

Abstract : The aim of this thesis is the study of magnetic tunnel junctions with perpendicularly magnetized electrodes (pMTJ), using perpendicular magnetic anisotropy (PMA) arising from the magnetic metal/oxide interfaces. For magnetic memories applications, it was predicted in theory that perpendicular junctions should need less energy (current) for spin transfer torque (STT) writing applications. However, the engineering of such structures is a real challenge and a difficult task since simultaneous transport (TMR) and PMA properties impose constraints on materials being used and also limit the working window of the device, especially in terms of magnetic layer thickness. In order to reach our goal we first studied different properties of these structures, such as the origin of PMA from the metal/oxide interface, tunnel transport and interlayer exchange coupling phenomena. The PMA at magnetic metal/oxide interface was showed to strongly depend on different parameters like annealing temperature, oxygen concentration, layer thickness etc. Several pMTJ structures were tested in order to choose the best one for MRAM memories applications. A correlation between TMR and PMA was observed and confirms the PMA origin from the magnetic metal-oxygen bond formation at the interface. Furthermore, antiferromagnetic interlayer exchange coupling was observed in our structures in the presence of out of plane anisotropy. A detailed study was made as a function of annealing temperature and layers thickness, in order to understand the origin of this coupling and its possible relationship to the anisotropy strength. Finally the STT-pMTJ concept was validated and low critical currents were observed on submicronic dots prepared by electron beam lithography.
Complete list of metadatas

Cited literature [224 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-00648593
Contributor : Abes Star <>
Submitted on : Tuesday, December 6, 2011 - 10:07:27 AM
Last modification on : Tuesday, May 14, 2019 - 5:45:39 PM
Long-term archiving on : Wednesday, March 7, 2012 - 2:30:10 AM

File

Nistor_Lavinia_2011_Archivage....
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-00648593, version 1

Collections

Citation

Lavinia Nistor. Jonctions tunnel magnétiques à aimantation perpendiculaire : anisotropie, magnétorésistance, couplages magnétiques et renversement par couple de transfert de spin. Autre [cond-mat.other]. Université Grenoble Alpes, 2011. Français. ⟨NNT : 2011GRENY046⟩. ⟨tel-00648593⟩

Share

Metrics

Record views

857

Files downloads

2349