Formation of nanosized Fe–Co alloys in α−Al2O3 crystals by ion implantation

Nanometer-sized Fe–Co composite clusters in α−Al2O3 matrices were synthesized by sequential implantation of Fe and Co ions with the projectiles’ energy at 100 keV. The synthesized clusters were shown to have bcc structure by the measurement of glancing angle x-ray diffraction. We have observed an apparent change in the internal magnetic field of the Fe–Co composite clusters with changing Co concentration, which exhibits the maximum at a concentration around 25 at. % Co as revealed by conversion electron Mössbauer spectroscopy. The magnetoresistance ratio of the granules was observed to increase with the Co addition to the Fe nanoclusters. The results provide clear evidences on the alloy formation of Fe–Co nanoclusters in α−Al2O3 layers synthesized by ion implantation.