Resonant frequencies of a binary magnetic nanowire

Abstract

Binary nanowires (Co50Fe50/Ni80Fe 20) that are 260-nm wide, 25-nm thick, and 4-mm long are fabricated using "self-aligned shadow deposition" lithography. Each wire is separated from the next by a gap of 115 nm. Ferromagnetic resonance experiments performed on the nanowires indicate resonant frequencies associated with the Co50Fe50 and the Ni80Fe20 parts of the nanowires. These frequencies are shifted from those measured in nanowires made from just one material or the other due to exchange and dipolar coupling between the two materials. A semianalytic theory is outlined that correctly predicts the resonant frequencies in the binary stripes at various values of static applied field. This calculation is checked against a micromagnetic simulation, and the agreement between both methods and the experiment is good. © 2013 American Physical Society.