Dresden 2009 – scientific programme

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MA: Fachverband Magnetismus

MA 30: Spin-Dynamics / Spin-Torque III

MA 30.2: Talk

Thursday, March 26, 2009, 10:30–10:45, HSZ 04

Non-adiabatic spin transfer torque in high anisotropy magnetic nanowires with narrow domain walls — •Jan Heinen, Olivier Boulle, Johannes Kimling, Mathias Kläui, and Ulrich Rüdiger — Fachbereich Physik, Universität Konstanz, Universitätsstrasse 10, 78457 Konstanz, Germany

The recent discovery that a spin polarized current can move a domain wall (DW) through a transfer of spin angular momentum opens a new path to manipulating magnetization without any external magnetic field. So far, current induced DW motion (CIDM) has been experimentally investigated in details for in-plane magnetized wires with a large DW widths (≥100 nm) where spin transfer is expected to occur in the “adiabatic limit". Here, we report on current driven depinning experiments of a narrow (≈6 nm) Bloch domain wall (DW) in perpendicularly magnetized (Pt/Co)₃ multilayer studied by magneto-transport. Such materials are ideal to tackle the key question of the non-adiabaticity of the spin transfer as a larger effect is expected due to the high DW magnetization gradient. We find that for conventional measurements, Joule heating effects conceal the real spin torque efficiency and so we use a measurement scheme at a constant sample temperature to unambiguously extract the spin torque contributions. From the variation of the depinning magnetic field with the current pulse amplitude, we directly deduce the large non-adiabaticity factor in this material and we find that its amplitude is consistent with momentum transfer [1].

[1] Boulle et al., Phys. Rev. Lett. 101, 216601 (2008).