We use frequency resolved magneto-optic Kerr effect to probe the spin-dynamics and mode structure in 50 to 200 nm diameter Ni80Fe20 nanomagnets ranging from 3 to 10 nm in thickness. We find that the intrinsic Gilbert damping parameter is largely unaffected by the nanopatterning process despite a large linewidth dependence on the size of the nanomagnets. In the larger nanomagnets, both end and center mode are observed. The linewidth of these two modes differ considerably, which is most likely the result of the sensitivity of the end mode to small variations and imperfection of the shape and edge material. We show that this effect can be exploited as a means to separately characterize the magnetic properties of the nanomagnets as well as the size and shape variations within the array.
Physical Review B
nanodots, magnetodynamics, spin dynamics, nanostructures, ferromagnetic resonance, nanomagnets