  Cylindrical magnetic nanowires are promising systems for the development of
three-dimensional spintronic devices. Here, we simulate the evolution of
magnetic states during fabrication of strongly-coupled cylindrical nanowires
with varying degrees of overlap. By varying the separation between wires, the
relative strength of exchange and magnetostatic coupling can be tuned. Hence
leading to the formation of six fundamental states as a function of both
inter-wire separation and wire height. In particular, two complex
three-dimensional magnetic states, a 3D Landau Pattern and a Helical Domain
wall, are observed to emerge for intermediate overlap. The competition of
magnetic interactions and the parallel growth scheme we follow (growing both
wires at the same time) favours the formation of these anti-parallel metastable
states. This works shows how the engineering of strongly coupled 3D
nanostructures with competing interactions can be used to create complex spin
textures.
