Direct Observation of Channelised Supercurrents in a Kagome Superconductor
Kagome超导体中通道化超流的直接观测
Matthijs Rog, Tycho J. Blom, Reinier Q. Regter, Andrea Capa Salinas, Dalal Benali, Jinwon Lee, Daan B. Boltje, Mark H. Fischer, Titus Neupert, Stephen D. Wilson, Milan P. Allan, Kaveh Lahabi
AI总结 利用SQUID显微镜直接观测到CsV3Sb5-xSnx薄片中窄超流通道网络,揭示其与约瑟夫森结阵列的关联,解释了反常输运现象。
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超导体是多体量子态,其中电流无耗散流动。理论预测,在常规和非常规超导体中,超流遵循相对简单的空间模式。最近对AV3Sb5(A = Cs, K, Rb)Kagome超导体家族的研究表明,CsV3Sb5具有这些简单理论无法解释的非常规输运性质,包括内禀约瑟夫森结、高阶库珀配对和零场二极管效应的报道。解释这些发现的尝试集中于超导性与这些材料中非常规电荷密度波(CDW)序的相互作用,超导性与CDW序相互竞争。目前理解这些Kagome超导体如何产生其有趣性质的一个障碍是缺乏输运的空间分辨信息。这里,我们利用最近开发的超导量子干涉器件(SQUID)显微镜,展示了CsV3Sb5-xSnx薄片中存在一个窄超流通道网络。这些超流通道在临界温度出现,并在所有温度和电流下保持稳定。它们的非线性行为与由窄超流丝连接的约瑟夫森结阵列一致,这自然导致了观测到的输运异常。有趣的是,这些观测在未掺杂样品中弱得多,这表明与电荷密度波、无序和电子关联的物理有关,所有这些都受到掺杂强度的极大影响。这些结果为强关联电子系统中电荷输运和竞争序的局域研究开辟了新前沿,并为AV3Sb5 Kagome超导体的反常输运性质提供了新视角。
Superconductors are many-body quantum states in which current flows without dissipation. Theory predicts that supercurrents follow a relatively simple spatial pattern in both conventional and unconventional superconductors. Recent studies into the AV3Sb5 (A = Cs, K, Rb) family of Kagome superconductors indicate that CsV3Sb5 has unconventional transport properties that cannot be accounted for with these simple theories, including reports of intrinsic Josephson junctions, higher order Cooper pairing and the zero field diode effect. Attempts to interpret these findings have focused on the interplay of superconductivity with the unconventional charge density wave (CDW) order in these materials, with which superconductivity competes. A current roadblock to understanding how these kagome superconductors give rise to their intriguing properties is the lack of spatially resolved information about transport. Here we show, using a recently developed superconducting quantum interference device (SQUID) microscope, that flakes of CsV3Sb5-xSnx host a network of narrow supercurrent channels. These supercurrent channels emerge at the critical temperature and remain stable for all temperatures and currents. Their non-linear behaviour is consistent with a network of Josephson junctions linked by narrow supercurrent filaments, which naturally leads to the observed transport anomalies. Intriguingly, these observations are much weaker in undoped samples, which suggests links to the physics of charge density waves, disorder, and electronic correlations, all of which are greatly influenced by the doping strength. These results establish new frontiers for the local investigation of charge transport and competing orders in strongly correlated electron systems, and shine a new light on the anomalous transport properties of the AV3Sb5 kagome superconductors.