# Conductance oscillations and zero-bias anomaly in a single superconducting junction to a three-dimensional $Bi_2Te_3$ topological insulator

## TL;DR

This study explores Andreev transport and conductance oscillations in a superconductor-topological insulator junction, revealing proximity-induced superconductivity effects in the topological surface state.

## Contribution

It provides experimental evidence of conductance oscillations and zero-bias anomalies linked to proximity-induced superconductivity in a Bi2Te3 topological insulator.

## Key findings

- Conductance oscillations are nearly periodic and occur in transparent junctions.
- Zero-bias conductance anomalies are observed alongside oscillations.
- Effects disappear above the superconducting transition or in resistive junctions.

## Abstract

We experimentally investigate Andreev transport through a single junction between an s-wave indium superconductor and a thick film of a three-dimensional $Bi_2Te_3$ topological insulator. We study $Bi_2Te_3$ 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 $In-Bi_2Te_3$ 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 $Bi_2Te_3$ topological surface state.