Interfacial Reaction-Associated Sample Quality and Superconductivity in Bi2Te3–FeTe Thin Films

The realization of atomic arrangement at the van der Waals interface is of importance in the exploration of interfacial superconductivity. Here, by epitaxy of Bi₂Te₃/FeTe heterostructures with different interface qualities, the corresponding atomic images and electron energy loss spectra evidence the relationship between interfacial chemical reaction and interface quality. Interfacial chemical reaction will cause the stoichiometric ratio imbalance of the FeTe layer and produce a large number of interstitial iron-related defects. When FeTe is employed as the growth substrate, it is crucial to maintain stable growth parameters for the Bi₂Te₃ layer. Conversely, when the Bi₂Te₃ layer serves as the growth substrate, ensuring a balanced stoichiometric ratio within the Bi₂Te₃ layer becomes paramount. This approach minimizes the extent of interface reactions and guarantees the stable presence of the superconducting phase at the interface. This work provides insights into the underlying relationship between interface structure and superconductivity in Bi₂Te₃/FeTe, and it reveals the possible mechanism by which neighboring telluride layers affect the topological superconductivity of FeTe heterostructures.