Magnetic properties of large-area particle arrays fabricated using block copolymer lithography

50-nm period arrays of Co particles with widths of 35 nm and heights of 5-20 nm have been made using a self-assembled block copolymer lithography. The magnetic particles have in-plane anisotropy due to their shape, and show thermally activated reversal with an activation volume larger than their physical volume, which is attributed to magnetic interactions between the particles.