高温超伝導体とグラフェンを組み合わせたデバイスで、新しい種類の量子輸送を発見(New kind of quantum transport discovered in a device combining high-temperature superconductors and graphene)

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2023-04-13 フィンランド・アールト大学

グラフェンと高温超伝導体を組み合わせた新しい量子デバイスが開発され、理論上予測された現象が実証された。グラフェンの特異な電子の振る舞いと高温超伝導体の特殊な量子状態を組み合わせることで、新しい電子トランスポートプロセスを実現した。
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>

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

高温超伝導体とグラフェンを組み合わせたデバイスで、新しい種類の量子輸送を発見(New kind of quantum transport discovered in a device combining high-temperature superconductors and graphene)

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. 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.

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