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Nucleation and propagation of magnetic domain walls in electrodeposited cylindrical nanowires

Mardi 29 mai 13:30 - Duree : 2 heures
Lieu : CNRS - Amphithéâtre-bâtiment A-3ème étage - 25 rue des Martyrs, Grenoble

Orateur : Soutenance de Thèse de Beatrix TRAPP

Magnetic domain walls in cylindrical nanowires have raised the interest of the scientific community due to their possible appli cation for innovative 3D memory as well as due to exciting new properties that arise from the geometric confinement. Situated in the framework of the European FP 7 project m3D, the objective of my work has been to investigate the motion of domain walls in nanowires with diameter modulations, by means of magnetic force microscopy and micromagnetic simulation. As domain wall energy increases with the wire diameter, the protrusions (resp. notches) are expected to act as an artificial energy barrier (resp. well). Thus a deterministic domain wall propagation controlled via the wire geometry seems possible. A first part of my work concerns material optimization. CoNi alloy wires (100-200nm diameter and multiple tens of microns in length) with two distinct geometries have been fabricated by template assisted electrodeposition. I have investigated the impact of alloy composition and possible annealing, on the microstructure and domain wall motion. In the second part, domain walls were investigated primarily with Magnetic Force Microscopy. On the best materials I succeeded in reliably nucleating domain walls with the assistance of a ns magnetic field pulse and to then propagate them with either quasistatic field or with only a ns field pulse. In addition to experiments, I have performed complementary micromagnetic simulations to investigate the effect of the modulation geometry.

Contact : beatrix.trapp@neel.cnrs.fr

Discipline évènement : (Physique)
Entité organisatrice : (Institut Néel / QUEST)
Nature évènement : (Soutenance de thèse)
Site de l'évènement : Polygone scientifique

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