Signatures of Edge States in Antiferromagnetic Van der Waals Josephson Junctions.

Abstract

The combination of superconductivity and magnetic textures leads to unconventional superconducting phenomena, including new correlated and topological phases. Van der Waals (vdW) materials emerge as a versatile platform for exploring the interplay between these two competing orders. Here, we report on individual <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics><msub><mi>NbSe</mi> <mn>2</mn></msub> <annotation>${\rm NbSe}_2$</annotation></semantics> </math> / <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics><msub><mi>NiPS</mi> <mn>3</mn></msub> <annotation>${\rm NiPS}_3$</annotation></semantics> </math> / <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics><msub><mi>NbSe</mi> <mn>2</mn></msub> <annotation>${\rm NbSe}_2$</annotation></semantics> </math> Josephson junctions behaving as superconducting quantum interference devices (SQUIDs), which we attribute to the interplay between the superconductivity of <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics><msub><mi>NbSe</mi> <mn>2</mn></msub> <annotation>${\rm NbSe}_2$</annotation></semantics> </math> and the spin texture of the vdW antiferromagnetic insulator <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics><msub><mi>NiPS</mi> <mn>3</mn></msub> <annotation>${\rm NiPS}_3$</annotation></semantics> </math> . This behavior persists for in-plane magnetic fields of at least 6 T and is the result of interference between separated transport channels. 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 channels that dominate transport. Our findings highlight AFI/S heterostructures as a platform for engineering novel superconducting phenomena and establish a new route for lithography-free SQUIDs that operate in high magnetic fields.