Oxygen-induced Fe surface segregation at the $L1_0$-FePd(001)/graphene heterointerface for spintronics devices: a first-principles study

Mitsuharu Uemoto; Naohiro Matsumoto; Ryusuke Endo; Samuel Vergara; Masaki Kobayashi; Hikari Shinya; Hiroshi Naganuma; Tomoya Ono

arXiv · 2502.00328

Oxygen-induced Fe surface segregation at the $L1_0$-FePd(001)/graphene heterointerface for spintronics devices: a first-principles study

Mitsuharu Uemoto·Naohiro Matsumoto·Ryusuke Endo·Samuel Vergara·Masaki Kobayashi·Hikari Shinya·Hiroshi Naganuma·Tomoya Ono

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Abstract

We theoretically investigate the atomic-scale structure of the heterointerface formed between the (001) surface of the $L1_0$-ordered iron palladium (FePd) intermetallic alloy and graphene (Gr), namely, $L1_0$-FePd(001)/Gr, which serves as an essential component in spintronic devices. Using density functional theory (DFT) calculations, we demonstrate that the topmost surface layer consisting of Pd (Pd-terminated surface) is energetically more stable than that consisting of Fe in vacuum, and that Pd-terminated surfaces are unfavorable for graphene adsorption. In contrast, under an oxygen atmosphere, the strong Fe--O bonding stabilizes Fe-terminated surfaces. The predicted Fe--O bonds on the oxidized surface are consistent with our X-ray photoelectron spectroscopy (XPS) measurements. These results reproduce the mechanism responsible for the graphene coverage observed in recent experiments. Similar oxygen-induced Fe surface segregation has been studied in heterogeneous catalysis on FePt and FePd alloys. In this work, we exploit this mechanism as a termination-engineering strategy to fabricate high-quality 2D-material/alloy heterointerfaces for nanoscale device applications.

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Mitsuharu Uemoto, Naohiro Matsumoto, Ryusuke Endo, Samuel Vergara, Masaki Kobayashi, Hikari Shinya, Hiroshi Naganuma, Tomoya Ono. 2025-02-01. Oxygen-induced Fe surface segregation at the $L1_0$-FePd(001)/graphene heterointerface for spintronics devices: a first-principles study. https://arxiv.org/abs/2502.00328

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