Superconductivity in Single-Quintuple-Layer Bi₂Te₃ Grown on Epitaxial FeTe

How an interfacial superconductivity emerges during the nucleation and epitaxy is of great importance not only for unveiling the physical insights but also for finding a feasible way to tune the superconductivity via interfacial engineering. In this work, we report the nanoscale creation of a robust and relatively homogeneous interfacial superconductivity (T_C ≈ 13 K) on the epitaxial FeTe surface, by van der Waals epitaxy of single-quintuple-layer topological insulator Bi₂Te₃. Our study suggests that the superconductivity in the Bi₂Te₃/FeTe heterostructure is generated at the interface and that the superconductivity at the interface does not enhance or weaken with the increase of the Bi₂Te₃ thickness beyond 1 quintuple layer (QL). The observation of the topological surface states crossing Fermi energy in the Bi₂Te₃/FeTe heterostructure with the average Bi₂Te₃ thickness of about 20 QL provides further evidence that this heterostructure may potentially host Majorana zero modes.