Tailoring the nucleation of domain walls along multi-segmented   cylindrical nanoelements
  The magnetization reversal of three-segment cylindrical nanoelements comprising of alternating nanowire and nanotube sections is investigated by means of Monte Carlo simulations. Such nanoelements may feature a three-state behaviour with an intermediate plateau in the hysteresis curve due to a metastable pinning of the domain walls at the wire-tube interfaces. It turns out that vortex as well as transverse domain walls contribute to the magnetization reversal. By varying the geometric parameters, the sequence, or the material of the elements the nucleation location of domain walls, as well as their nucleation field, can be tailored. Especially interesting is the novel possibility to drive domain walls coherently in the same or in opposite directions by changing the geometry of the hybrid nanoelement. This important feature adds additional flexibility to the construction of logical devices based on domain wall movement. Another prominent outcome is that domain walls can be nucleated near the centre of the element and then traverse to the outer tips of the cylindrical structure when the applied field is increased, which also opens the possibility to use these three-segment nanoelements for the field induced delivery of domain walls as substitutes for large nucleation pads. 
R. F. Neumann, M. Bahiana, S. Allende, D. Altbir, D. G\"orlitz, K.   Nielsch
cond-mat.mes-hall physics.comp-ph