Low-ordering-temperature fabrication of FePt by ion irradiation

A low temperature ordering of L1₀ FePt phase was directly achieved by using 2-MeV He-ion irradiation without conventional post-annealing. The coercivity greater than 5700 Oe can be obtained by using ion-irradiation heating at temperature as low as 230°C. The high beam-current-density results in direct beam heating on samples. In addition, the irradiation-induced heating process provides efficient microscopic energy transfer and creates excess point defects, which significantly enhances the diffusion and promotes the formation of the ordered phase.