Interfacing Two Topological Insulators, α -Bismuthene and β -Silicene, with a Rare-Earth Magnetic Monolayer

Abstract The integration of diverse electronic phenomena, such as magnetism and nontrivial topology, into a single low-dimensional system gives rise to unusual quantum effects. Here we combine two 2D topological insulators, α-bismuthene and β-silicene, with a Ho monolayer. Bismuthene is synthesized within a rarely realized square-like lattice in the black phosphorus monolayer structure, and its interfacing with the silicene minimizes the unwanted hybridization with the Ho monolayer, thus facilitating a quasi-free-standing behavior. The spectroscopy observations together with ab initio calculations indicate the emergence of robust topological edge states, suggesting the fabricated interface as a promising platform to exploit the quantum spin Hall effect and coherent spin transport properties. Using in situ magnetotransport measurements combined with theoretical predictions, we probe the critical magnetic temperature and discuss probable magnetic ordering at the interface. Our findings suggest new pathways for interfacing 2D materials possessing diverse quantum effects for advanced spintronics applications.