2023-04-13 フィンランド・アールト大学
この研究成果は、グラフェン量子デバイスの新たな開発の可能性を示し、量子技術デバイスの新たなプラットフォームを確立することができる。
＜関連情報＞
- https://www.aalto.fi/en/news/new-kind-of-quantum-transport-discovered-in-a-device-combining-high-temperature-superconductors-and
- https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.130.156201
高温超伝導体-グラフェン接合におけるアンドレーエフ反射とクライントンネリング Andreev Reflection and Klein Tunneling in High-Temperature Superconductor-Graphene Junctions
Sharadh Jois, Jose L. Lado, Genda Gu, Qiang Li, and Ji Ung Lee
Physical Review Letters Published 12 April 2023
DOI:https://doi.org/10.1103/PhysRevLett.130.156201
ABSTRACT
Scattering processes in quantum materials emerge as resonances in electronic transport, including confined modes, Andreev states, and Yu-Shiba-Rusinov states. However, in most instances, these resonances are driven by a single scattering mechanism. Here, we show the appearance of resonances due to the combination of two simultaneous scattering mechanisms, one from superconductivity and the other from graphene p−n junctions. These resonances stem from Andreev reflection and Klein tunneling that occur at two different interfaces of a hole-doped region of graphene formed at the boundary with superconducting graphene due to proximity effects from Bi2Sr2Ca1Cu2O8+δ. The resonances persist with gating from p+−p and p−n configurations. The suppression of the oscillation amplitude above the bias energy which is comparable to the induced superconducting gap indicates the contribution from Andreev reflection. Our experimental measurements are supported by quantum transport calculations in such interfaces, leading to analogous resonances. Our results put forward a hybrid scattering mechanism in graphene–high-temperature superconductor heterojunctions of potential impact for graphene-based Josephson junctions.
