Tuning the Curie temperature of a two-dimensional magnet/topological insulator heterostructure to above room temperature by epitaxial growth

Abstract

The heterostructures of 2D magnets and topological insulators are attractive candidates for quantum anomalous hall effect and highly-efficient spin-orbit torque switching. To better study these phenomena, it will be crucial to synthesize epitaxial heterostructures for scalability while maintaining high-quality interfaces to preserve the topological surface states and having the Curie temperature (T${}_{C}$) above room temperature. Here, the authors utilize molecular beam epitaxy to tune the T${}_{C}$ in heterostructures of van der Waals (vdW) magnet Fe${}_{3}$GeTe${}_{2}$ and topological insulator Bi${}_{2}$Te${}_{3}$ to above room temperature by varying growth conditions. Electron microscopy reveals the existence of thicker vdW compounds in the Fe${}_{m}$Ge${}_{n}$Te${}_{2}$ family, as well as some intercalants in between vdW gaps, which are possible origins for the enhanced T${}_{C}$.