Fast propagation of weakly-pinned domain walls and current-assisted magnetization reversal in He+-irradiated Pt/Co/Pt nanotracks

Current developments of magnetic data storage and processing technologies make highly desirable to control fast and reproducible magnetic-domain-wall motion in narrow magnetic tracks, using either magnetic field or electrical current. For this purpose, nanotracks defined in ultrathin magnetic films with out-of-plane anisotropy seem to be particularly interesting. However, in most of the out-of-plane metallic nanosystems which were studied up to now, domain-wall pinning was shown to still play a predominant role, which resulted in low domain-wall velocities, as compared to the ones observed in plain magnetic films [1].
Using magneto-optical microscopy, we show that in an etched Pt/Co/Pt nanotrack with out-of-plane anisotropy, where pinning has been artificially reduced by He+-irradiation [2], weakly-pinned domain-walls can propagate as fast and under magnetic fields as low as in the corresponding plain irradiated film (Fig. 1) [3]. Moreover, when magnetic-field and electrical-current pulses are simultaneously applied to the track, a considerably faster magnetization reversal is observed, which is due to a Joule-heating-induced thermomagnetic effect [3].
This work was partially supported by the EU-“Research Infrastructures Transnational Access” program “Center for Application of Ion Beams in Materials Research” under contract no. 025646, and by the French ANR-07-NANO-034 “Dynawall” project.
* now at Radboud University Nijmegen, Institute for Molecules and Materials, Netherlands
[1] F. Cayssol et al., Phys. Rev. Lett. 92, 107202 (2004).
[2] C. Chappert et al., Science 280, 1919 (1998).
[3] M. Cormier et al., submitted (2011).