Curvature-driven ac-assisted creep dynamics of magnetic domain walls

The dynamics of micrometer-sized magnetic domains in ultrathin ferromagnetic films is so dramatically slowed down by quenched disorder that the spontaneous elastic tension collapse becomes unobservable at ambient temperature. By magneto-optical imaging we show that a weak zero-bias ac magnetic field can assist such curvature-driven collapse, making the area of a bubble to reduce at a measurable rate, in spite of the negligible effect that the same curvature has on the average creep motion driven by a comparable dc field. An analytical model explains this phenomenon quantitatively.

Automated summary

The dynamics of micrometer-sized magnetic domains in ultrathin ferromagnetic films is slowed down significantly by quenched disorder, making spontaneous elastic tension collapse unobservable at ambient temperature. However, a weak zero-bias ac magnetic field was found to assist curvature-driven collapse, reducing the area of a bubble at a measurable rate, despite negligible effect on average creep motion driven by a comparable dc field. An analytical model quantitatively explains this phenomenon.