Induced superconductivity and engineered Josephson tunneling devices in epitaxial (111)-oriented gold/vanadium heterostructures

TL;DR

This paper demonstrates a novel method to induce superconductivity in epitaxial gold films on vanadium, enabling the creation of Josephson devices with potential applications in topological quantum computing.

Contribution

It introduces an epitaxial growth technique for (111) gold films on vanadium, achieving high-quality interfaces and inducing superconductivity suitable for nano device engineering.

Findings

Superconductivity observed in Au thin films below 4 K.

Clear Josephson tunneling and Andreev reflection in heterostructures.

Barrier thickness affects tunneling and subharmonic gap structures.

Abstract

We report a unique experimental approach to create topological superconductors by inducing superconductivity into epitaxial metallic thin film with strong spin-orbit coupling. Utilizing molecular beam epitaxy technique under ultra-high vacuum condition, we are able to achieve (111) oriented single phase of gold (Au) thin film grown on a well-oriented vanadium (V) s-wave superconductor film with clean interface. We obtained atomically smooth Au thin films with thicknesses even down to below a nanometer showing near-ideal surface quality. The as-grown V/Au bilayer heterostructure exhibits superconducting transition at around 4 K. Clear Josephson tunneling and Andreev reflection are observed in S-I-S tunnel junctions fabricated from the epitaxial bi-layers. The barrier thickness dependent tunneling and the associated subharmonic gap structures (SGS) confirmed the induced superconductivity in Au (111), paving the way for engineering thin film heterostructure based p-wave superconductors and nano devices for Majorana fermion.