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Asymmetric energy potential of pinned domain walls at constrictions
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
2008 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 93, no 17, 172508- p.Article in journal (Refereed) Published
Abstract [en]

The pinning properties of magnetic vortex domain walls were experimentally investigated in patterned nanowires with artificial constrictions. Domain walls were nucleated and depinned by applied magnetic fields and observed with magnetic force microscopy. It was found that the pinning strength is dependent on the chirality of the vortex wall. Micromagnetic simulations confirm these results and reveal the energy potential of the pinned domain wall, including the width of the pinning site.

Place, publisher, year, edition, pages
2008. Vol. 93, no 17, 172508- p.
National Category
Engineering and Technology
URN: urn:nbn:se:uu:diva-97832DOI: 10.1063/1.3009287ISI: 000260571800058OAI: oai:DiVA.org:uu-97832DiVA: diva2:172917
Available from: 2008-11-19 Created: 2008-11-19 Last updated: 2016-04-13Bibliographically approved
In thesis
1. Tailored Properties of Ferromagnetic Thin Films
Open this publication in new window or tab >>Tailored Properties of Ferromagnetic Thin Films
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Magnetic thin films and patterned nanostructures have been studied with respect to their magnetic properties using SQUID-magnetometry, magnetic force microscopy, electrical measurements, and micromagnetic calculations.

Properties of vortex domain walls, trapped in Permalloy nanowires with artificial constrictions, were investigated experimentally and by numerical calculations. In particular, the geometrical extent and strength of the pinning potential were evaluated. In these wires, long-range vortex domain wall displacement induced by spin polarized alternating currents was obtained numerically at reduced threshold current densities as compared with the direct current case. Due to the asymmetry of the energy potential, the long-range displacement direction is determined by the vortex chirality.

Strained FeCo/Pt superlattices with strong perpendicular anisotropy were investigated experimentally. The strain was controlled by varying the thickness of each alternating layer with monolayer precision and was found to have a dominating effect on the total anisotropy.

Epitaxial films of the diluted magnetic semiconductor (Ga,Mn)As were studied with focus on how the ferromagnetic transition temperature could be controlled by post-growth annealing. The ferromagnetic transition temperature was enhanced by approximately 85% for a Mn-doping concentration of 6% under certain conditions.

A method to manipulate micrometer sized magnetic particles on patterned arrays of elliptical Permalloy microstructures was studied. Controlled motion and separation of the magnetic particles were obtained using applied rotating magnetic fields. The domain structure of the elliptical elements was studied numerically.

Place, publisher, year, edition, pages
Uppsala: Universitetsbiblioteket, 2008. 97 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 579
micromagnetics, domain wall, vortex, pinning potential, nanowire, spin dynamics, spin transfer torque, magnetic anisotropy, MFM, Permalloy, PMA, magnetic multilayer, Curie temperature, DMS, GaMnAs, magnetic bioseparation
National Category
Other Engineering and Technologies
urn:nbn:se:uu:diva-9403 (URN)978-91-554-7353-2 (ISBN)
Public defence
2008-12-11, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:15 (English)
Available from: 2008-11-19 Created: 2008-11-19 Last updated: 2011-11-16Bibliographically approved

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