Precise determination of moire pattern in monolayer FeO(111) films on Au(111) by scanning tunneling microscopy

Monolayer iron-oxide films are attractive for both spintronic application and surface chemical catalysis. However, the detailed atomic structure of the FeO monolayer which is crucial for understanding the physical and chemical properties of the films is not well understood. In this work, we fabricate high-quality monolayer FeO films on the Au(111) substrate by molecular-beam epitaxy. High-resolution scanning tunneling microscopy measurements simultaneously reveal the close-packed atomic arrangement and hexagonal moire pattern of the monolayer FeO and were combined with hexagonal commensurate mode calculations to establish the atomic structure of the monolayer FeO(111) with respect to the Au(111) substrate. The identification of this stable commensurate arrangement of FeO(111) monolayer on Au(111) paves the way for the exploration of its fundamental science and its applications in industry.