Inducing superconductivity in Weyl semi-metal microstructures by selective ion sputtering

TL;DR

This paper demonstrates a novel method to induce superconductivity in Weyl semi-metal NbAs microstructures through selective ion sputtering, enabling potential topological quantum device fabrication.

Contribution

It introduces a reliable ion irradiation technique to create superconducting layers on non-superconducting Weyl semi-metals, facilitating topological device development.

Findings

Superconducting NbAs microstructures achieved with Tc~3.5K.

Ion sputtering enriches Nb at the surface, forming a superconducting layer.

Method enables scalable fabrication of topological quantum devices.

Abstract

By introducing a superconducting gap in Weyl- or Dirac semi-metals, the superconducting state inherits the non-trivial topology of their electronic structure. As a result, Weyl superconductors are expected to host exotic phenomena such as non-zero-momentum pairing due to their chiral node structure, or zero- energy Majorana modes at the surface. These are of fundamental interest to improve our understanding of correlated topological systems, and moreover practical applications in phase coherent devices and quantum applications have been proposed. Proximity-induced superconductivity promises to allow such experiments on non-superconducting Weyl semi-metals. Here we show a new route to reliably fabricating superconducting microstructures from the non-superconducting Weyl semi-metal NbAs under ion irradiation. The significant difference in the surface binding energy of Nb and As leads to a natural enrichment of Nb at the surface during ion milling, forming a superconducting surface layer (Tc~3.5K). Being formed from the target crystal itself, the ideal contact between the superconductor and the bulk may enable an effective gapping of the Weyl nodes in the bulk due to the proximity effect. Simple ion irradiation may thus serve as a powerful tool to fabricating topological quantum devices from mono-arsenides, even on an industrial scale.