Composite domain walls in flat nanomagnets: the magnetostatic limit
  We discuss the structure of the so-called "vortex" domain walls in soft magnetic nanoparticles. A wall of this kind is a composite object consisting of three elementary topological defects: two edge defects with winding numbers -1/2 and a vortex with a winding number +1 between them. We provide a qualitative model accounting for the energetics of such a domain wall. 
H. Youk, G.-W. Chern, K. Merit, B. Oppenheimer, O. Tchernyshyov