First-principles study of surface structure estimation in $L{1}_0$-FePd(001)/graphene heterojunction

In this paper, we present a theoretical and computational investigations of the atomic scale structure of the heterointerface formed between the (001) surface of $L{1}_0$-ordered iron palladium (FePd) alloy and graphene (Gr), namely, $L{1}_0$-FePd(001)/Gr. Using density functional theory (DFT) calculations, we demonstrate that the topmost surface layer consisting of Pd (Pd-terminated surface) becomes more energetically stable than Fe, and Pd-terminated surfaces are not conducive to Gr adsorption. On the other hand, under oxygen atmosphere conditions, our calculation suggests the presence of Fe-terminated surfaces with Gr-covered structures reproducing recent experimental observations. Moreover, the finding of Fe–O bonds formed by oxidizated surface is also consistent with those of X-ray photoelectron spectroscopy. These findings are crucial for understanding the fabrication processes of interfaces in Fe-based $L{1}_0$ alloy materials.