Electronic structure and magnetic properties of the metastable $$\hbox {Au}_{1-x}\hbox {Fe}_{x}$$ Au 1 - x Fe x alloy films

A set of the metastable at room temperature (RT) $$\hbox {Au}_{1-x}\hbox {Fe}_{x}$$ Au 1 - x Fe x alloy films ( $$0.01\le \hbox {x}\le 0.98$$ 0.01 ≤ x ≤ 0.98 ) were fabricated using DC RT magnetron co-sputtering of Au and Fe targets. It was shown that the solid solution of Fe in face-centered cubic (FCC) Au is formed in $$\hbox {Au}_{1-x}\hbox {Fe}_{x}$$ Au 1 - x Fe x alloy films for $$0.01\le \hbox {x}\le 0.77$$ 0.01 ≤ x ≤ 0.77 . At $$x\approx 0.80$$ x ≈ 0.80 , the transition from the FCC type to body-centered cubic (BCC)-type ordered $$\hbox {Au}_{1-x}\hbox {Fe}_{x}$$ Au 1 - x Fe x alloy films takes place. The first-principle calculations of the density of electronic states, the cohesive energies, and element resolved magnetic moments ( $$m_{Au}$$ m Au and $$m_{Fe}$$ m Fe ) have been performed for FCC-type ordered structures $$\hbox {L1}_{2}$$ L1 2 - $$\hbox {Au}_{0.75}\hbox {Fe}_{0.25}$$ Au 0.75 Fe 0.25 , $$\hbox {L1}_{0}$$ L1 0 - $$\hbox {Au}_{0.50}\hbox {Fe}_{0.50}$$ Au 0.50 Fe 0.50 , and $$\hbox {L1}_{2}$$ L1 2 - $$\hbox {Au}_{0.25}\hbox {Fe}_{0.75}$$ Au 0.25 Fe 0.75 . The calculations reveal that among these alloys, the $$\hbox {Au}_{0.25}\hbox {Fe}_{0.75}$$ Au 0.25 Fe 0.75 is the most stable as having the largest cohesive energy. It was also shown that both Au and Fe atoms contribute to the calculated resulting magnetic moment $$M_{AuFe}$$ M AuFe of $$\hbox {Au}_{1-x}\hbox {Fe}_{x}$$ Au 1 - x Fe x alloys but have an opposite compositional dependence on Fe content. The general decrease in calculated magnetic moment of $$\hbox {Au}_{1-x}\hbox {Fe}_{x}$$ Au 1 - x Fe x alloys $$M_{AuFe}$$ M AuFe with a decrease in x nicely agrees with the experimentally determined compositional dependence of magnetic properties of $$\hbox {Au}_{1-x}\hbox {Fe}_{x}$$ Au 1 - x Fe x alloy films. Unlike the literature results, the experimentally determined M(x) dependence shows two different parts related to the films with FCC type or BCC type of structure. Graphical abstract