Antiphase domain boundaries (APDBs) in the (√2 × √2)R45° reconstruction of the Fe3O4(001) surface were investigated using scanning tunneling microscopy (STM) and density functional theory (DFT+U) calculations. The equilibrium structure of the APDBs is interpreted in terms of the distorted B-layer model for the (√2 × √2)R45° reconstruction, in which a lattice distortion couples to charge order in the subsurface layers. The APDBs are observed after prolonged annealing at 700 °C, indicating that they are extremely stable. DFT+U calculations reveal that the APDB structure is linked to a disruption in the subsurface charge order pattern, leading to an enrichment of Fe2+ cations at the APDB. Simulated STM images reproduce the appearance of the APDBs in the experimental data and reveal that they are preferential adsorption sites for hydrogen atoms.
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Corresponding author: Gareth S. Parkinson (parkinson).