Magnetization dynamics: ultra-fast and ultra-small

Ultrafast magnetic processes are of great scientific interest but also form the basis of high density magnetic recording applications. We demonstrate the uniqueness of time resolved, high resolution magnetic X-ray microscopy, and show that the motion of a magnetic vortex core can be imaged. The vortex core direction is hidden to most experimental techniques, but has a decisive influence on the dynamics of the magnetic structure. We imaged the switching of a ferromagnetic nano-structure by a spin polarized current pulse using time resolved X-ray microscopy. As opposed to the common uniform switching process due to Neel and Stoner-Wohlfarth, the magnetization in spin injection devices does not switch uniformly, but involves the motion of a magnetic vortex. (author)