Self-assembled magnetic nanostructures of CoPt ₃ with favoured chemical ordering

CoPt 3 (111) nanostructures, prepared by self-assembled growth on WSe 2 (0001) substrates, present a 111-oriented fcc structure with a hexagonal island shape and a relatively narrow size distribution. L1 2 -type ordering is already observed in nanostructures grown at 150°C, a temperature considerably lower than that required to order CoPt 3 continuous films. This change is attributed to the nanoscopic island shape, which increases the possibilities of surface atomic arrangements provided by the different growing facets. From the superparamagnetic behavior of the nanostructures, a strong decrease of magnetic anisotropy with the occurrence of L1 2 ordering is deduced.