Superconducting density of states at the border of an amorphous thin film grown by focused-ion-beam

TL;DR

This study uses low-temperature STM/S to investigate how superconducting properties evolve at the border of an amorphous W-based thin film grown by focused-ion-beam, revealing changes in conductance and vortex behavior near the substrate.

Contribution

It provides detailed experimental insights into the superconducting density of states at the film's border, especially near the Au substrate, using advanced STM/S techniques.

Findings

Superconducting tunneling conductance increases near the Au substrate.

Quasiparticle peaks remain stable approaching the substrate.

Vortex lattice observed close to the Au substrate.

Abstract

We present very low temperature Scanning Tunneling Microscopy and Spectroscopy (STM/S) measurements of a W based amorphous thin film grown with focused-ion-beam. In particular, we address the superconducting properties close to the border, where the thickness of the superconducting film decreases, and the Au substrate emerges. When approaching the Au substrate, the superconducting tunneling conductance strongly increases around the Fermi level, and the quasiparticle peaks do not significantly change its position. Under magnetic fields, the vortex lattice is observed, with vortices positioned very close to the Au substrate.