Induced Superconductivity in Hybrid Au/YBa2Cu3O7-x Electrodes on Vicinal Substrates

TL;DR

This paper reports on the fabrication and characterization of hybrid Au/YBa2Cu3O7-x electrodes on vicinal substrates, revealing induced superconductivity in gold layers with potential for high-temperature Josephson devices.

Contribution

It introduces a novel Au/YBCO electrode structure on vicinal substrates that enhances induced superconductivity in gold layers, demonstrated through STM and transport measurements.

Findings

Energy gap of 10-17 meV observed in gold layer

Multiple Andreev reflections confirm superconductivity in gold

Higher and more consistent induced gap compared to conventional structures

Abstract

Superconducting electrodes are an integral part of hybrid Josephson junctions used in many applications including quantum technologies. We report on the fabrication and characterization of superconducting hybrid Au/YBa2Cu3O7-x (YBCO) electrodes on vicinal substrates. In these structures, superconducting CuO2-planes face the gold film, resulting in a higher value and smaller variation of the induced energy gap compared to the conventional Au/YBCO electrodes based on films with the c-axis normal to the substrate surface. Using scanning tunneling microscopy, we observe an energy gap of about 10-17 meV at the surface of the 15- nm-thick gold layer deposited in situ atop the YBCO film. To study the origin of this gap, we fabricate nanoconstrictions from the Au/YBCO heterostructure and measure their electrical transport characteristics. The conductance of the nanoconstrictions shows a series of dips due to multiple Andreev reflections in YBCO and gold providing clear evidence of the superconducting nature of the gap in gold. We consider the Au/YBCO electrodes to be a versatile platform for hybrid Josephson devices with a high operating temperature.