笼目超导体SrSn₃中独特的表面与体超导性
Distinct Surface and Bulk Superconductivity in the Kagome Superconductor SrSn$_3$
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中文总结 AI 辅助
本研究通过调控扫描隧道光谱的隧穿结电阻，在笼目超导体SrSn₃的外延薄膜中区分出具有不同特性的表面与体超导通道，揭示了涡旋芯电子结构与超导通道的依赖关系，为拓扑量子材料的涡旋束缚态研究提供了新认知。
中文摘要 AI 辅助
在具有非平庸电子结构的量子材料中，表面与体超导性可能具有根本不同的超导特性，但它们叠加的光谱特征常常阻碍对每个超导通道的直接实验获取。本文中，我们通过调整扫描隧道光谱中的隧穿结电阻，在笼目超导体SrSn₃的外延薄膜中揭示了具有显著不同超导能隙、上临界场和涡旋芯电子态的独特表面与体超导通道。表面超导性的特征为不依赖于厚度的超导能隙和增强的上临界场，而体超导通道则表现出更大的超导能隙，该能隙随薄膜厚度减小而降低，且具有低得多的上临界场。在磁场涡旋芯内，稳健的非分裂零偏置电导峰仅在表面超导通道中被观测到，而明显的零偏置抑制始终与体超导通道相关联。这些发现表明，涡旋芯电子结构敏感地依赖于潜在的超导通道，为拓扑量子材料中的涡旋束缚态提供了新的见解。
英文摘要
Surface and bulk superconductivity may possess fundamentally different superconducting properties in quantum materials with nontrivial electronic structures, yet their superimposed spectroscopic signatures often prevent direct experimental access to each superconducting channel. Here we reveal, in epitaxial films of the kagome superconductor SrSn$_3$, distinct surface and bulk superconducting channels with markedly different superconducting gaps, upper critical fields, and vortex-core electronic states by tuning the tunneling junction resistance in scanning tunneling spectroscopy. The surface superconductivity is characterized by a thickness-independent superconducting gap and an enhanced upper critical field, whereas the bulk superconducting channel exhibits a larger superconducting gap that decreases with reducing film thickness and a much lower upper critical field. Within magnetic vortex cores, robust non-split zero-bias conductance peaks are observed exclusively in the surface superconducting channel, while pronounced zero-bias suppression is consistently associated with the bulk superconducting channel. These findings demonstrate that the vortex-core electronic structure depends sensitively on the underlying superconducting channel, providing new insight into vortex-bound states in topological quantum materials.
