Oxide Antiferromagnetics as Barrier Materials for Josephson Junctions Based on Cuprate Superconductor

Electron transport studies of superconducting hybrid Josephson mesa-structures with antiferromagnetic barriers attract huge interest for their specific magnetic field dependences of superconducting current and possibility of spin-triplet pairing. We will exploit two antiferromagnetic materials: Ca1–xSrxCuO2 and Sr2IrO4. The first one is A-type canted antiferromagnet, while the second one exhibits strong spin-orbit coupling that favorers spin-triplet pairing. In this study characteristics of superconducting transport in Josephson junctions YBaCuO/Sr2IrO4/Au-Nb are obtained. Barrier heights of 20 meV and localization radii α of 1.5 nm for Sr2IrO4 were estimated. The radii were smaller than the α values for Ca0.5Sr0.5CuO2 that is of 4–10 nm. The features of superconducting transport: DC Josephson effect with similar critical current and normal resistance products in order of ICRN 50 µV, AC Josephson effect with presence of second harmonic of current-phase relation, are common for mesa-structures with the two kinds of barriers.