# Interfacial superconductivity induced by single-quintuple-layer Bi$_2$Te$_3$ on top of FeTe forming van-der-Waals heterostructure

## TL;DR

This study demonstrates interfacial superconductivity in a van-der-Waals heterostructure of Bi$_2$Te$_3$ on FeTe, with a transition temperature of 13 K, revealing potential mechanisms involving charge transfer and proximity effects.

## Contribution

First observation of interfacial superconductivity in a Bi$_2$Te$_3$/FeTe heterostructure, highlighting the role of charge transfer and interface effects in inducing superconductivity.

## Key findings

- Superconductivity observed at 13 K on Bi$_2$Te$_3$/FeTe heterostructure.
- Superconducting gap decays exponentially with Bi$_2$Te$_3$ thickness.
- Charge transfer may induce hole doping in FeTe, contributing to superconductivity.

## Abstract

We report the first clear observation of interfacial superconductivity on top of FeTe(FT) covered by one quintuple-layer Bi$_2$Te$_3$(BT) forming van-der-Waals heterojunction. Both transport and scanning tunneling spectroscopy measurements confirm the occurrence of superconductivity at a transition temperature T$_c$ = 13~K, when a single-quintuple-layer BT is deposited on the non-superconducting FT surface. The superconductivity gap decays exponentially with the thickness of BT, suggesting it occurs at the BT-FT interface and the proximity length is above 5-6~nm. We also measure the work function's dependence on the thickness of BT, implying a charge transfer may occur at the BT/FT interface to introduce hole doping into the FT layer, which may serve as a possible candidate for the superconducting mechanism. Our BT/FT heterojunction provides a clean system to study the unconventional interfacial superconductivity.