0-pi transitions in Josephson junctions with antiferromagnetic interlayers

TL;DR

This paper demonstrates that superconductor-antiferromagnet-superconductor Josephson junctions exhibit atomic-scale 0 or pi phase states depending on the interlayer thickness, with temperature-induced transitions due to spin-split bound states.

Contribution

It reveals the atomic-scale dependence of Josephson phase states on AF interlayer thickness and temperature, highlighting the role of symmetry and spin-split states.

Findings

0 or pi junction states depend on even or odd atomic layers

Temperature can induce 0-pi transitions in odd-layer junctions

Spin-split Andreev bound states drive phase transitions

Abstract

We show that the dc Josephson current through superconductor-antiferromagnet-superconductor (S/AF/S) junctions manifests a remarkable atomic scale dependence on the interlayer thickness. At low temperatures the junction is either a 0- or pi-junction depending on whether the AF interlayer consists of an even or odd number of atomic layers. This is associated with different symmetries of the AF interlayers in the two cases. In the junction with odd AF interlayers an additional pi-0 transition can take place as a function of temperature. This originates from the interplay of spin-split Andreev bound states. Experimental implications of these theoretical findings are discussed.