Conductance oscillations and zero-bias anomaly in a single superconducting junction to a three-dimensional $B{i}_{2}T{e}_3$ topological insulator

Abstract

We experimentally investigate Andreev transport through a single junction between an s-wave indium superconductor and a thick film of a three-dimensional $B{i}_{2}T{e}_3$ topological insulator. We study $B{i}_{2}T{e}_3$ samples with different bulk and surface characteristics, where the presence of a topological surface state is confirmed by direct ARPES measurements. All the junctions demonstrate Andreev transport within the superconducting gap. For junctions with transparent $In-B{i}_{2}T{e}_3$ interfaces we find a number of nearly periodic conductance oscillations, which are accompanied by zero-bias conductance anomaly. Both effects disappear above the superconducting transition or for resistive junctions. We propose a consistent interpretation of both effects as originating from proximity-induced superconducting correlations within the $B{i}_{2}T{e}_3$ topological surface state.

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