Regensburg 2010 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 33: Poster II
MA 33.16: Poster
Freitag, 26. März 2010, 11:00–14:00, Poster B1
Evolution of magnetoresistance in electromigrated ferromagnetic break junctions — •Arndt von Bieren1, Ajit Kumar Patra1, Stephen Krzyk1, Jakoba Heidler1, Jan Rhensius1,2, Laura Heyderman2, Regina Hoffmann3, and Mathias Kläui1 — 1Fachbereich Physik, Universität Konstanz, Germany — 2Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, Villingen, Switzerland — 3Physikalisches Institut, Universität Karlsruhe, Germany
Recently, magnetotransport measurements of magnetic nanocontacts have led to a better understanding of the interactions between spin-polarized charge carriers and magnetization taking place at extremely small length scales. Here, we present the evolution of magnetoresistance (MR) in clean electrical break junctions. Ferromagnetic nanocontacts with variable constriction width are fabricated by performing in-situ controlled electromigration of notched magnetic half ring structures in UHV. Low temperature MR measurements, in agreement with micromagnetic simulations, indicate that the dominant contribution in Py (Ni80Fe20) contacts down to the size of a few nm is anisotropic magnetoresistance (AMR). Moreover, Ni shows enhanced AMR in constrictions approaching the atomic limit and high tunnelling anisotropic magnetoresistance (TAMR) after carefully opening the contact, suggesting that material-specific parameters such as the electron mean free path play a crucial role. By analyzing the angle-dependent MR we can furthermore extract the domain wall pinning strength of the constriction as a function of its size down to the atomic scale.