# Multifaceted impact of a surface step on superconductivity in atomically thin films

## TL;DR

This paper demonstrates how atomic surface steps significantly influence superconductivity in ultrathin films, affecting electronic structure, order parameter distribution, and transport properties, thus enabling tailored superconducting devices.

## Contribution

It reveals the multifaceted effects of surface steps on superconductivity in atomically thin films using self-consistent Bogoliubov-de Gennes calculations, highlighting new ways to engineer superconducting circuits.

## Key findings

- Surface steps modify electronic structure on both sides of the step.
- Superconducting order parameter distribution is affected by the step.
- Transport properties depend on step height, influencing Josephson effects.

## Abstract

Recent experiments show that an atomic step on the surface of atomically thin metallic films can strongly affect electronic transport. Here we reveal multiple and versatile effects that such a surface step can have on superconductivity in ultrathin films. By solving the Bogoliubov-de Gennes equations self-consistently in this regime, where quantum confinement dominates the emergent physics, we show that the electronic structure is profoundly modified on the two sides of the step, as is the spatial distribution of the superconducting order parameter and its dependence on temperature and electronic gating. Furthermore, the surface step changes non-trivially the transport properties both in the proximity-induced superconducting order parameter and the Josephson effect, depending on the step height. These results offer a new route to tailor superconducting circuits and design atomically thin hetero-junctions made of one same material.