The study of Fe@FeCo and Fe@FeCo@Au core-shell structure by the First-principles theory

Abstract

In this article, we study the FeCo core-shell structure and Au-covered FeCo core-shell structure using the First-principles theory. We study the difference of electronic property, magnetic moment and optical property with or without Au shell covered. We find that the O2 binding energy of the FeCo core-shell structure has decreased largely when covered with Au layer, namely, their oxidation resistance will improve markedly. At the same time the magnetic moment of Co and Fe has also been maintained. In addition, we consider the influence of the solution and the results show that the O2 binding energy decreases with the increase of the dielectric media of the solution, indicating the effect of the dielectric media of the solution on the electron transfer. As the Au atoms has arresting optical property, we also survey the effect of Au shell on Fe1@Fe6Co8@Au42, Fe1@Fe6Co8@Au84 and Fe22Co58@Au170. The different effects of core and outer Au on the optical absorption spectrum were researched and the results show that the more Au in the outer layer affects the adsorption of higher frequencies and the larger FeCo core affects the absorption of light in the lower frequencies. Stronger magnetic moment and excellent optical property would expand its application in medicine and biology areas.