晶界工程对超导薄膜中涡旋物质的影响
Grain Boundary Engineering Effect on Vortex Matter in Superconducting Films
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中文总结 AI 辅助
本研究揭示溅射压力可调控NbTiN薄膜的晶界耦合，改变涡旋物质的分布与钉扎性能，为定制多晶超导薄膜的涡旋钉扎提供了实用方法。
中文摘要 AI 辅助
多晶超导薄膜中的晶界（GBs）是一把双刃剑：它们既可以钉扎涡旋，也可通过类约瑟夫森弱连接耦合降低超导性能。本文证明溅射压力可调控NbTiN薄膜中的晶界耦合，并可视化其对涡旋物质的影响：5 mTorr薄膜呈现分散的晶粒取向，外加磁场下存在两步电阻转变，表明其具有晶间弱连接行为；相比之下，7 mTorr薄膜形成（111）织构，呈现单步转变，具备更高的临界电流密度、第二磁化峰，以及符合晶界耦合改善的δl型钉扎响应。低温磁力显微镜观测显示，5 mTorr薄膜中存在空间异质的簇状涡旋构型，而7 mTorr薄膜则具有更均匀的分布与增强的局域有序性。这些结果确立了沉积调控的晶界连通性、宏观弱连接输运与微观涡旋组织之间的关联，为定制多晶超导薄膜的涡旋钉扎提供了实用途径。
英文摘要
Grain boundaries (GBs) in polycrystalline superconducting films act as a double-edged sword: they can pin vortices or degrade superconductivity through Josephson-like weak-link coupling. Here, we demonstrate that sputtering pressure tunes GB coupling in NbTiN films and visualize its consequences for vortex matter. The 5 mTorr film exhibits dispersed grain orientations and a two-step resistive transition under field, signaling intergranular weak-link behavior. In contrast, the 7 mTorr film develops a (111) texture, a single-step transition, higher critical current density, a second magnetization peak, and a δl-type pinning response consistent with improved GB coupling. Cryogenic magnetic force microscopy reveals a spatially heterogeneous, cluster-like vortex configuration in the 5 mTorr film, whereas the 7 mTorr film hosts a more uniform distribution with enhanced local order. These results establish a connection between deposition-controlled GB connectivity, macroscopic weak-link transport, and microscopic vortex organization, providing a practical route to tailor vortex pinning in polycrystalline superconducting films.
