Vortex-antivortex pairs induced by curvature in toroidal nanomagnets
  We show that the curvature of nanomagnets can be used to induce chiral textures in the magnetization field. Among the phenomena related to the interplay between geometry and magnetic behavior at nanomagnets, an effective curvature-induced chiral interaction has been recently predicted. In this work, it is shown that a magnetization configuration consisting of two structures with opposite winding numbers (vortex and antivortex) appear as remanent states in hollow toroidal nanomagnets. It is shown that these topological configurations are a result of a chiral interaction induced by curvature. In this way, the obtained results present a new form to produce stable vortices and antivortices by using nanomagnets with variable curvature. 
Smiljan Vojkovic, Vagson L. Carvalho-Santos, Jakson M. Fonseca, Alvaro   S. Nunez
cond-mat.mes-hall