Structural and Magnetic Stabilities of Fe Bilayers on Cu(111)

Structural and magnetic stability of Fe bilayer films on Cu(111) substrate was investigated from first-principles calculations, in which two atomic-stackings are considered for the fct-like and bct-like phases of the Fe bilayers. When a ferromagnetic (FM) alignment of the Fe bilayer is assumed, the surface Fe atoms energetically favor the bridge sites (bct-like phase) better than the hollow sites (fct-like phase). On the contrary, for an antiferromagnetic (AFM) alignment, the fct-like phase becomes favorable. The results suggest that the bi-stability of the FM and AFM structures may lead to the coexistence of the fct-like and bct-like phases observed in experiments.