Superparamagnetic regular nanopillar-like structures studied by grazing-incidence X-ray scattering: effect of vertical correlation

Grazing-incidence small-angle X-ray scattering is reported from nanoclusters in superparamagnetic (SPM) polycrystalline Co separated by Au. The self-organization of the Co nanoclusters is in the form of nanopillar-like structures with high perpendicular magnetic anisotropy. A distinct signature of regular near-neighbour ordering is observed, which is commonly observed in patterned nanostructures. The estimated cluster sizes corroborate with those estimated from their magnetic field response. Most significantly, the SPM limit for these clusters can be raised to above room temperature (∼325 K) with an increase in the vertical correlation of the nanopillars. The slow response time of these uniform nanomagnetic grains (with respect to a 10 kHz AC field) suggests their possible usage as potential magnetic storage devices in the form of three-dimensional nanopillars.