Regensburg 2007 – scientific programme
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MA: Fachverband Magnetismus
MA 12: Spindependent Transport I
MA 12.6: Talk
Tuesday, March 27, 2007, 11:30–11:45, H22
FIB-structured nanoconstrictions for the study of domain wall magnetoresistance — •Daniel Stickler1, Robert Frömter1, Holger Stillrich1, Yun Zhou2, Genhua Pan2, and Hans Peter Oepen1 — 1Institut für Angewandte Physik, Universität Hamburg, Jungiusstr. 11, 20355 Hamburg , Germany — 2CRIST, Faculty of Technology, University of Plymouth, Plymouth, Devon PL4 8AA, UK
Several fundamentally and technologically interesting physical effects emerge when spin polarized currents in a ferromagnet pass through a laterally confined domain wall. We pursue different approaches for the fabrication of suitable structures for domain wall pinning which are based upon direct FIB (Focused Ion Beam) structuring. Our FIB is operating under ultrahigh vacuum condition. While the lateral resolution for imaging is 6 nm, the smallest structures written so far are 20nm. First results on 70 nm wide constrictions in a current in plane (CIP) geometry are presented. The experiments have been performed in a homogenous external field. Specifically shaped magnetic pads are used as a spin reservoir for injection. In 3 nm Ta / 8 nm NiFe / 3 nm Ta multilayers characteristic jumps in the magneto resistance (MR) are found which indicate the controlled injection of a domain wall into the constriction. We have also investigated the magneto resistance in a current perpendicular to plane (CPP) geometry. A cobalt point contact (smaller than 30 nm) has been fabricated by filling a pinhole milled into a silicon-nitride membrane. Financial support by the EU via EU04-586 "BMR" is gratefully acknowledged.