Dresden 2011 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 43: Micro- and Nanostructured Magnetic Materials IV
MA 43.3: Vortrag
Mittwoch, 16. März 2011, 17:30–17:45, HSZ 103
Beyond a compact magnetic domain wall — •Philipp Eib, Carl Zinoni, Antoine Vanhaverbeke, Gian Salis, Andreas Bischof, and Rolf Allenspach — IBM Research - Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
The generally accepted concept that limits magnetic domain wall velocity is the Walker breakdown: It determines the magnetic field at which the wall motion becomes turbulent [1]. This sets an upper limit on the performance of domain wall-based spintronic devices.
To understand the limiting mechanisms, we study domain wall dynamics in Ni80Fe20 wires with widths between 300 and 900 nm. A time-resolved magneto-optical Kerr effect setup with pump-probe technique is used to detect the moving walls. The wires are fabricated by electron-beam lithography and our nanostencil tool [2].
We find the dynamics of vortex walls to depart significantly from the current description of a compact entity evolving along the wire; instead, the wall is composed of several substructures, each one propagating and evolving in a different dynamic regime with very different velocities. Extensive, parallelized micromagnetic simulations reveal the unusual wall structure and complement the experimental findings. From the insight gained into this complex dynamics we discuss possibilities how to overcome the limits imposed by the Walker breakdown.
[1] R. Cowburn and D. Petit, Nature Mater. 4, 721 (2005)
[2] L. Gross, R. R. Schlittler, G. Meyer, and R. Allenspach, Nanotechnology 21, 325301 (2010)