Interfacial Superconductivity and Zero Bias Peak in Quasi‐One‐Dimensional Bi 2 Te 3 /Fe 1+y Te Heterostructure Nanostructures

Bismuth telluride/iron telluride (Bi 2 Te 3 /Fe 1+y Te) heterostructures are known to exhibit interfacial superconductivity between two non‐superconducting materials: Fe 1+y Te as the parent compound of Fe‐based superconducting materials and the topological insulator Bi 2 Te 3 . Here, a top‐down approach is presented starting from 2D heterostructures to fabricate 1D Bi 2 Te 3 /Fe 1+y Te nanowires or narrow nanoribbons. It is demonstrated that the Bi 2 Te 3 /Fe 1+y Te 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 Bi 2 Te 3 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 Fe 1+y Te layer, developing in parallel with superconductivity at low temperatures.