Regensburg 2013 – scientific programme

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MA: Fachverband Magnetismus

MA 50: Poster II

MA 50.60: Poster

Friday, March 15, 2013, 10:30–13:30, Poster D

Magneto-resistance in electromigrated magnetic nanocontacts — •André Loescher¹, Mohamad-Assaad Mawass^1,5, Robert M. Reeve¹, Jakoba Heidler², Jan Rhensius^2,3, Laura J. Heyderman², Regina Hoffmann⁴, and Mathias Kläui^1,2,3 — ¹Johannes Gutenberg-Universität Mainz, Germany — ²Paul Scherrer Institut, Villigen, Switzerland — ³Universität Konstanz, Germany — ⁴Physikalisches Institut and DFG-Center for Functional Nanostructures, Karlsruhe Institute of Technology, Germany — ⁵Max-Planck-Institut für Intelligente Systeme, Stuttgart, Germany

Magnetotransport measurements on magnetic nanocontacts have been performed with the aim to understand the interactions between spin-polarized charge carriers and magnetization on the nanoscale. Here, we study the evolution of magnetoresistance (MR) in electromigrated ferromagnetic junctions obtained in clean ultra-high vacuum (UHV) conditions. While previously Permalloy (Ni₈₀Fe₂₀) nanocontacts with variable constriction width have been investigated, the fundamental behaviour of magnetization in such nanocontacts is not fully understood, with measurement artifacts often complicating the interpretation of results. In-situ controlled electromigration of notched half ring structures was performed in order to tailor the size of the contact. The MR was measured as a function of the constriction width in order to study the magnetic properties and characterize the strength and extent of the domain wall pinning potential. Furthermore, the MR ratio at remanence is observed to reach 50% and exhibit a previously unobserved sign change in contacts that approach the atomic limit.