Proximity effect and electron transport in the oxide hybrid heterostructures with superconducting/magnetic interfaces

TL;DR

This study investigates electron transport and the proximity effect in oxide heterostructures with superconductor/magnetic interfaces, revealing long-range superconducting correlations and magnetic field sensitivity in specific antiferromagnetic layered structures.

Contribution

The paper presents a theoretical and experimental analysis of long-range proximity effects in S/M heterostructures with antiferromagnetic interlayers, highlighting unique superconducting and magnetic interactions.

Findings

Long-range proximity effect observed at S/AF interfaces.

Superconducting critical current density of 1-10A/cm² at 15-50 nm AF interlayer.

Deviation from standard current-phase relation with significant second harmonic component.

Abstract

We report on the study of electron transport in the oxide heterostructures with superconductor/magnetic matter (S/M) interfaces where anomaly large penetration of superconducting correlations in magnetic matter (proximity effect) is realized. The developed theoretical model based on multilayer magnetic structure of M-interlayer and experiment show presence of the long-range proximity effect at S/M-interface with antiferromagnetic (AF) ordering of the interlayer magnetization. The investigated hybrid heterostructures include cuprate superconductor, the AF-cuprate interlayer and conventional superconductor, Nb. The superconducting critical current with density 1-10A/cm2 and the characteristic voltage, 0.1-0.2 mV, are observed at liquid helium temperature for 15-50 nm thick M-interlayer made of AF film CaSrCuO. These heterostructures demonstrate deviation from sin-type superconducting current-phase relation and had the critical current of the second harmonic of 10-20% of the first harmonic one. The hybrid heterostructures with S/AF interface show high sensitivity to the external magnetic field that is possibly caused by the influence of an external magnetic field on the canting of magnetic moments of individual layers of AF -interlayer. Substituting the AF cuprate by a manganite film, no critical current was observed, although the M- interlayer was made very thin, down to 5 nm.