Doubling of the magnetic energy product in ferromagnetic nanowires at ambient temperature by capping their tips with an antiferromagnet

We present an approach to prepare free-standing tips of micrometer-long nanowires electrodeposited in anodic aluminum oxide nanopores. Such open tips can be further processed, e.g. for vertical interconnects of functional layers or for tailoring the magnetization reversal of ferromagnetic nanowires. The magnetic switching of nanowires is usually initiated by vortex or domain formation at the nanowire tips. We show that coating the tips of Fe₃₀Co₇₀ nanowires (diameter 40 nm, length 16 μ m) with thin antiferromagnetic Fe₅₀Mn₅₀ capping layers (thickness ≈10 nm) leads to magnetic hardening with a more than doubled energy product at ambient temperature. (paper)