Ferromagnetic CoPt₃ nanowires: Structural evolution from fcc to ordered L1₂

This investigation demonstrates the magnetic properties and nanostructures of CoPt₃ wire arrays that were fabricated by electrodeposition using a porous alumina template. The X-ray absorption analysis clearly verified the occurrence of a phase transition in CoPt₃ nanowires. This phase transition significantly influences the magnetic properties and enhances coercivity and squareness. The phase transition of CoPt₃ nanowires was from a random alloy distribution to anisotropically ordered CoPt₃ (L1₂). The thermally induced phase transition of CoPt₃ nanowires to ordered L1₂ CoPt₃ through a "cluster-in-cluster" intermediate state via interdiffusion processes is revealed. The mechanism exhibited by these CoPt₃ nanowires is proposed to explain the strong correlation between their magnetic character and their atomic distribution.