Synthesis of Two-Dimensional Iron Boride on Au(111)

Two-dimensional (2D) transition metal borides have attracted extensive attention due to their unique electronic, magnetic, and catalytic properties. In particular, 2D Fe-B systems, which are predicted as ideal 2D magnetic arrays, have never been realized successfully. Here, we report the first synthesis of 2D Fe–B monolayer on Au(111) via molecular beam epitaxy. Scanning tunneling microscopy measurements reveal the regular order and lattice periodicity of the Fe–B monolayer. First-principles calculations reproduce the key topographic and spectroscopic features, validating the proposed structural model and indicating a dominant contribution of Fe 3d states in the electronical bands. Further experiments reveal the 2D Fe–B monolayer can service as template for the regular physical adsorption of individual Fe adatoms. This work also establishes a bottom-up strategy for synthesizing family of 2D MBenes.