L10 CoPt–Cu nanoparticles for high-density magnetic recoding by sol–gel technique

Abstract CoPt alloys nanoparticles with different content of CoPt and Cu were prepared at various temperatures by sol–gel method. The L1 0 CoPt with 50 at.% Cu addition was obtained when the annealing temperature was 600 °C. Compared to the pure CoPt nanoparticles, no obvious coalescence was observed for the CoPt–Cu 50 at.% particles and particle sizes were uniform. Cu presence suppressed the activation energy from the chemically disordered face-centered cubic structure to face-centred tetragonal structure transformation and enhanced the ordered reaction. The magnetic properties of CoPt–Cu nanoparticles were also improved.