  Perpendicular magnetic anisotropy [Co/Pd]15 and L10-FePt nanowire arrays of
period 63 nm with linewidths 38 nm and 27 nm and film thickness 27 nm and 20 nm
respectively were fabricated using a self-assembled PS-b-PDMS diblock copolymer
film as a lithographic mask. The wires are predicted to support Neel walls in
the Co/Pd and Bloch walls in the FePt. Magnetostatic interactions from nearest
neighbor nanowires promote a ground state configuration consisting of
alternating up and down magnetization in adjacent wires. This was observed over
~75% of the Co/Pd wires after ac-demagnetization but was less prevalent in the
FePt because the ratio of interaction field to switching field was much
smaller. Interactions also led to correlations in the domain wall positions in
adjacent Co/Pd nanowires. The reversal process was characterized by nucleation
of reverse domains, followed at higher fields by propagation of the domains
along the nanowires. These narrow wires provide model system for exploring
domain wall structure and dynamics in perpendicular anisotropy systems.
