Signatures of edge states in antiferromagnetic van der Waals Josephson junctions

TL;DR

This paper demonstrates that van der Waals heterostructures with antiferromagnetic insulators can host edge states that produce SQUID behavior, even under high magnetic fields, revealing new superconducting phenomena.

Contribution

It introduces a new platform of vdW Josephson junctions with antiferromagnetic insulators exhibiting edge states and high-field SQUID operation, advancing topological and superconducting research.

Findings

Observation of SQUID behavior in NbSe2/NiPS3/NbSe2 junctions.

Persistence of SQUID interference under magnetic fields of at least 6 T.

Microscopic modeling indicating localized edge states dominate transport.

Abstract

The combination of superconductivity and magnetic textures represents a promising approach to explore unconventional superconducting phenomena, including new correlated and topological phases. Van der Waals (vdW) materials have emerged in this context as a versatile platform to explore the interplay between these two competing orders. Here, we report on individual NbSe2/NiPS3/NbSe2 vdW Josephson junctions behaving as superconducting quantum interference devices (SQUIDs), which we attribute to the interplay between the superconductivity of NbSe2 and the spin texture of the vdW antiferromagnetic insulator NiPS3. The SQUID behavior, which persists for in-plane magnetic fields of at least 6 T, is the result of interference between localized transport channels that form in two separate regions of the sample. Microscopic modeling of the antiferromagnet insulator/superconductor (AFI/S) interface reveals the formation of localized states at the edges of the junction that can lead to localized channels that dominate the transport. Our findings highlight the potential of vdW superconducting heterostructures with AFs as platforms for engineering and probing novel superconducting phenomena, and they establish a new route for lithographic-free SQUIDs that operate in high magnetic fields.