Spin-Mixing Enhanced Proximity Effect in Aluminum-Based Superconductor-Semiconductor Hybrids
Spin-Mixing Enhanced Proximity Effect in Aluminum-Based Superconductor-Semiconductor Hybrids
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DOI：
10.1002/adma.202202034
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发表时间：
2022-07-14
影响因子：
29.4
通讯作者：
Kouwenhoven, Leo P.
中科院分区：
文献类型：
--
作者：
Mazur, Grzegorz P.;van Loo, Nick;Kouwenhoven, Leo P.
在超导量子电路中，铝是应用最广泛的材料之一。它目前也是拓扑量子比特开发所选用的超导体。然而，铝基器件存在磁场兼容性差的问题。在此，通过表明重元素（例如铂）的吸附原子可使铝薄膜的临界磁场提高两倍多，这一限制得以解决。利用隧道结表明，增强的磁场耐受性源自铂引入的自旋 - 轨道散射。在半导体 - 超导体混合结构的超导近邻效应背景下利用了这一特性，结果表明与铝/铂薄膜强耦合的锑化铟纳米线在高达7特斯拉的磁场下仍能保持超导性。结果显示，双电子充电效应在重吸附原子存在的情况下依然稳健。此外，在三端结构中使用非局域光谱来探测混合器件的主体，表明其没有亚带隙态。最后，证明了近邻化的半导体态在施加磁场时保持其塞曼分裂的能力。结合铝的化学稳定性和众所周知的制造工艺，铝/铂成为铝基系统的自然替代品，并且在需要高场耐受性时，是其他超导体的一个极具吸引力的替代选择。
In superconducting quantum circuits, aluminum is one of the most widely used materials. It is currently also the superconductor of choice for the development of topological qubits. However, aluminum-based devices suffer from poor magnetic field compatibility. Herein, this limitation is resolved by showing that adatoms of heavy elements (e.g., platinum) increase the critical field of thin aluminum films by more than a factor of two. Using tunnel junctions, it is shown that the increased field resilience originates from spin-orbit scattering introduced by Pt. This property is exploited in the context of the superconducting proximity effect in semiconductor-superconductor hybrids, where it is shown that InSb nanowires strongly coupled to Al/Pt films can maintain superconductivity up to 7 T. The two-electron charging effect is shown to be robust against the presence of heavy adatoms. Additionally, non-local spectroscopy is used in a three-terminal geometry to probe the bulk of hybrid devices, showing that it remains free of sub-gap states. Finally, it is demonstrated that proximitized semiconductor states maintain their ability to Zeeman-split in an applied magnetic field. Combined with the chemical stability and well-known fabrication routes of aluminum, Al/Pt emerges as the natural successor to Al-based systems and is a compelling alternative to other superconductors, whenever high-field resilience is required.