MnBr$_2$ on the graphene on Ir(110) substrate: growth, structure, and super-moiré

Single-layer MnBr$_2$ is grown on graphene (Gr) supported by Ir(110) and investigated using low-energy electron diffraction, scanning tunneling microscopy, and spectroscopy. The structure and epitaxial relationship with the substrate are systematically characterized. The growth morphology strongly depends on the growth temperature, evolving from fractal to dendritic and eventually to compact dendritic skeletal islands, reflecting changes in the underlying surface diffusion processes. MnBr$_2$ on Gr/Ir(110) constitutes a three-lattice system, giving rise to a super-moiré pattern --a moiré of moirés. Due to the involvement of lattices of differing symmetries and the partial electronic transparency of Gr, a "virtual" moiré formed by MnBr$_2$ and Ir(110) contributes to the super-moiré formation. Ab initio calculations play a crucial role in understanding the complexity of super-moiré. Moreover, the pronounced variation in the apparent height with tunneling conditions for the magnetic insulator is explained based on the measured electronic structure.