Evidence of Josephson coupling in a few-layer black phosphorus planar Josephson junction

TL;DR

This paper provides the first evidence of Josephson coupling in a planar black phosphorus junction, demonstrating supercurrent flow and Fraunhofer patterns, which opens new avenues for quantum technologies using van der Waals materials.

Contribution

It reports the first observation of proximity Josephson coupling in a planar black phosphorus junction, expanding the scope beyond graphene-based systems.

Findings

Supercurrent flow observed at milli Kelvin temperatures.

Fraunhofer pattern confirmed Josephson coupling.

Gate-tunable junction behavior demonstrated.

Abstract

Setting up strong Josephson coupling in van der Waals materials in close proximity to superconductors offers several opportunities both to inspect fundamental physics and to develop novel cryogenic quantum technologies. Here we show evidence of Josephson coupling in a planar few-layer black Phosphorus junction. The planar geometry allows us to probe the junction behavior by means of external gates, at different carrier concentrations. Clear signatures of Josephson coupling are demonstrated by measuring supercurrent flow through the junction at milli Kelvin temperatures. Manifestation of Fraunhofer pattern with a transverse magnetic field is also reported, confirming the Josephson coupling. These findings represent the first evidence of proximity Josephson coupling in a planar junction based on a van der Waals material beyond graphene and open the way to new studies, exploiting the peculiar properties of exfoliated black phosphorus thin flakes.