Synthesis of nanosized FeCo granular alloys by ion implantation and TMR effect

In this study we present an eminent enhancement of magnetoresistance (MR) effect in FeCo alloy nanocomposite prepared by sequential implantation of 100 keV 57Fe and 59Co ions into Al2O3 matrices. We investigated the MR effect in the granules with changing the relative amount of Fe and Co implanted to total fluences of (1.0–1.2) × 1021 ions/m2 and found a systematic change of MR ratio with a maximum effect around Co concentration of 25 at.%. The obtained MR ratio at room temperature and at external field H = 8.8 ×105 A/m is 13.2% and it is the highest value reported among the Fe, Co and FeCo granular films.