X-ray magnetic circular dichroism studies of the enhancement of Fe spin moment in (Fe_(70)Co_(30)/Pd)_n superlattice films with high saturation magnetization

摘要

It was reported that magnetic materials reveal a high saturation magnetization above 2.45 T, which is known as the highest saturation magnetization of Fe_(70)Co_(30) alloy in nature. An (Fe_(70)Co_(30)/Pd)_n superlattice film with optimized sublayer thickness showed that the saturation magnetization of the Fe_(70)Co_(30) sublayers and that of the whole film were 2.66 and 2.57 T, respectively. These values were defined as an average of the magnetic moments of Fe, Co, and Pd atoms, and the contribution ratio of each element to the magnetization improvement is still not clear. X-ray magnetic circular dichroism measurement enabled a direct estimation of the individual moments of Fe, Co, and Pd atoms in the superlattice film and it clarified that the magnetization improvement in the superlattice films was induced by an enhancement of Fe spin moment dominantly in the Fe_(70)Co_(30) sublayers. These results follow the other theoretical and experimental results about an enhancement of the Fe moment of atoms which are laminated with Pd layers.