由莫尔霍夫施塔特光谱实现的高场约瑟夫森效应
High-field Josephson effect enabled by a moiré Hofstadter spectrum
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中文总结 AI 辅助
研究利用莫尔工程化石墨烯约瑟夫森结克服磁场对超导干涉测量的限制，通过弹道石墨烯/hBN结实现相位相干安德列夫输运，展示高场约瑟夫森干涉，为高场超导干涉测量建立新平台。
中文摘要 AI 辅助
磁场通常会抑制相位相干的约瑟夫森输运，将超导干涉测量限制在相对低的场强。本文表明，莫尔工程化的石墨烯约瑟夫森结可以克服这一限制。利用弹道石墨烯/hBN结，通过法布里 - 珀罗振荡和夫琅禾费干涉建立了相位相干的安德列夫输运，其在主狄拉克锥和重构的莫尔微带中均持续存在。然后在分形霍夫施塔特 - 蝴蝶区域展示了高达6 T的相位相干约瑟夫森干涉，远超传统弹道石墨烯结预期范围。与霍夫施塔特光谱计算对比表明，在莫尔势将具有淬灭群速度的朗道能级转变为具有有限准粒子群速度的色散磁布洛赫带的地方，超导得以存续，实现了跨结的扩展电子 - 空穴安德列夫轨迹。结果表明霍夫施塔特微带可在传统上与量子霍尔 regime相关的参数域深处稳定相位相干超导，为高场超导干涉测量建立了新平台。
英文摘要
Magnetic fields generally suppress phase-coherent Josephson transport, limiting superconducting interferometry to relatively low fields. Here we show that moiré-engineered graphene Josephson junctions can overcome this constraint. Using ballistic graphene/hBN junctions, we establish phase-coherent Andreev transport through Fabry-Pérot oscillations and Fraunhofer interference that persist across both the primary Dirac cone and reconstructed moiré minibands. We then demonstrate phase-coherent Josephson interference up to 6 T in the fractal Hofstadter-butterfly regime, well beyond the range expected for conventional ballistic graphene junctions. Comparison with Hofstadter-spectrum calculations reveals that superconductivity survives where the moiré potential transforms Landau levels with quenched group velocity into dispersive magnetic Bloch bands with finite quasiparticle group velocity, enabling extended electron-hole Andreev trajectories across the junction. Our results show that Hofstadter minibands can stabilize phase-coherent superconductivity deep into the parameter domain conventionally associated with the quantum Hall regime, establishing a new platform for high-field superconducting interferometry.
