High-throughput directed self-assembly of core-shell ferrimagnetic nanoparticle arrays.

Magnetic nanoparticles (MNPs) provide a set of building blocks for constructing stimuli-responsive nanoscale materials with properties that are unique to this scale. The size and the composition of MNPs are tunable to meet the requirements for a range of applications including biosensors and data storage. Although many of these technologies would significantly benefit from the organization of nanoparticles into higher-order architectures, the precise placement and arrangement of nanoparticles over large areas of a surface remain a challenge. Herein, we demonstrate the viability of magnetic nanoparticles for patterned recording media utilizing a template-directed self-assembly process to afford well-defined nanostructures of magnetic nanoparticles and access these assemblies using magnetic force microscopy and a magnetic recording head. Photolithographically defined holes were utilized as templates to form assemblies of ferrimagnetic nanoparticle rings or pillars selectively over a large area (>1 cm(2)) in just 30 s. This approach is applicable to other nanoparticle systems as well and enables their high-throughput self-assembly for future advanced device fabrication.