Interfacial Superconductivity and Zero Bias Peak in Quasi‐One‐Dimensional Bi₂Te₃/Fe_1+yTe Heterostructure Nanostructures

Abstract

Bismuth telluride/iron telluride (Bi2Te3/Fe1+yTe) heterostructures are known to exhibit interfacial superconductivity between two non‐superconducting materials: Fe1+yTe as the parent compound of Fe‐based superconducting materials and the topological insulator Bi2Te3. Here, a top‐down approach is presented starting from 2D heterostructures to fabricate 1D Bi2Te3/Fe1+yTe nanowires or narrow nanoribbons. It is demonstrated that the Bi2Te3/Fe1+yTe heterostructure remains intact in nanostructures of widths on the order of 100 nm and the interfacial superconductivity is preserved, as evidenced by electrical transport and Andreev reflection point contact spectroscopy experiments measured at the end of the nanowire. The differential conductance shows a similar superconducting twin‐gap structure as in 2D heterostructures, but with enhanced fluctuation effects due to the lower dimensionality. A zero‐bias conductance peak indicates the presence of an Andreev bound state and, given the involvement of the topological Bi2Te3 surface state, a possible topological nature of superconductivity is discussed with strong interplay with an emerging ferromagnetism due to the interstitial excess iron (Fe) in the Fe1+yTe layer, developing in parallel with superconductivity at low temperatures.