Time-resolved X-ray Microscopy of Magnetic Antivortex Dynamics

The study of magnetic singularities, vortices and antivortices, has recently intensified as they have been suggested as non-volatile data storage elements or for spin-wave logic applications. Magnetic antivortices occur during the switching process of their topological counterparts, the vortices [1], as well as in crosstie-domain walls and special geometries [2]. Understanding the dynamics of antivortices [3] is therefore fundamental for gaining a detailed knowledge necessary to design new spintronic applications. Here we show by time-resolved X-ray microscopy experiments that magnetic antivortices indeed gyrate when excited by alternating currents, in agreement with theoretical models and micromagnetic simulations [3], albeit with much lower efficiency than their topological counterparts, the vortices. [1] B. Van Waeyenberge et al., Nature \textbf{444}, 461 (2006). [2] K.Shigeto et al., APL \textbf{80}, 4190, (2002). [3] A. Drews et al., PRB \textbf{77}, 094413 (2008); B. Krueger et al., JAP \textbf{103}, 07A501 (2008).