The influence of Sb doping in achieving high magnetic coercivities in CoPt nanoparticles for micromagnet applications.

The use of magnetic elements within microelectronic devices are increasingly required in the fabrication of miniature magnetic structures with high energy densities. A synthesis technique is reported that yields Sb-doped CoPt nanoparticles possessing magnetic coercivities as high as 1671 kA/m and magnetic remanences of 295 kA/m, providing an energy product of 20 kJ/m2. Antimony doping was shown to influence the atomic ordering within the alloy sublattices, which allowed the tetragonalization temperature of the nanoparticle structure to be lowered by 200 °C to 400 °C, thereby reducing crystallite growth and sintering during annealing. The ¿as-synthesized¿ particles had average diameters of 4.5 nm, which rose to 25 nm on annealing at 600 °C. Synthesis of the doped CoPt particles with high-energy products together with control of particle size distributions in the range of 25 nm allows fabrication of micromagnetic structures by conventional microfabrication techniques such as spin coating and ink-jet printing.