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D-wavE Proximitiy effects in Topological Hybrids

Periodic Reporting for period 1 - DEPTH (D-wavE Proximitiy effects in Topological Hybrids)

Reporting period: 2021-09-01 to 2023-08-31

This Project addressed the challenge of experimentally studying proximity effects and Josephson coupling between high-temperature, d-wave superconductors and Van der Waals (VdW) 2D materials, using solid-state devices. The goal was to demonstrate the transmission of cooper pairs at the interface between d-wave superconductor and VdW materials, Josephson coupling mediated by the VdW, and exotic effects linked to its presence, all probed by transport measurements.

It is important for society as it represents a strong demonstration of the possibility of coupling high temperature superconducting oxides with 2D materials to realize superconducting circuits, allowing to create new functionalities for superconducting electronics working at nitrogen temperatures.

The Objectives of the project were to characterize the proximity effect and Andreev Reflection at single d-wave superconductor/VdW interface, as well as realizing d-wave superconductor/VdW/d-wave superconductor Josephson junction.

This action allowed to study multiple fundamental and experimental aspects of superconducting heterostructures combining d-wave superconductors and low dimension materials. It allowed for the development of state of the art planar heterostructures combining HTc materials with materials in the 2D limit and large scale growth of 2D VdW structures on HTc materials, as well as their characterization. It allowed the beneficiary to develop this activity and helped him to get a permanent position in the host institution.
During the project, we realized multiple milestones to complete the objectives of the project. In particular, we characterized and modeled proximity effect between d-wave superconducting oxides and metals using a planar geometry and state of the art fabrication techniques involving superconducting high-temperature superconductors. We also developed transfer techniques to handle 2D materials and characterized the proximity effect between d-wave superconducting oxides and 2D VdW materials. Finally, we realized Josephson junctions using such materials.
The obtained results have been presented on multiple occasions at conferences through the community and will allow for developing more advance superconducting devices.
Multiple milestones have been achieved during this project, representing state of the art in the field of superconducting junctions involving d-wave superconductors and 2D materials. In particular:
1/ We studied for the first-time proximity effect in planar Superconducting/Metal junctions made with the d-wave superconductor YBCO and an irradiation process. These junctions demonstrated an exceptional transparency and really rich behaviour with was first modeled by the young researcher, and is now being modeled by Sebastian Bergeret’s team by using a dedicated model encompassing the rich encountered physics.
2/ We developed techniques to transfer and study proximity effects in dichalcogenides induced by proximity with d-wave HTc superconductors and measured proximity effect in planar d-wave/dichalcogenide junctions and the first evidences of proximity effect in such structures.
3/ We realized state of the art deposition of dichalcogenide on superconducting and the first circuits coupling d-wave HTc superconductor with such materials. In addition, it allowed us to realize superconducting circuits coupling d-wave HTc superconductor with dichalcogenides.
Experiments involving the integration of d-wave high temperature superconductors and their characterization by transport measurements are still extremely rare, and all the instances discussed above represent significant advancements with high potential impact
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