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

Here we combine two 2D topological insulators, <i>α</i>-bismuthene and <i>β</i>-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 <i>ab initio</i> 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 <i>in situ</i> magnetotransport measurements combined with theoretical predictions, we probe the critical magnetic temperature and discuss probable magnetic ordering at the interface.