AI 中文总结
本研究针对聚焦氦离子束辐照制备的YBCO弱连接，基于扩散型SNS结模型分析其约瑟夫森输运，揭示临界电流等特性的剂量依赖机制，为相关结设计提供了扩散框架。
AI 中文摘要
通过聚焦氦离子束辐照制备YBCO弱连接，是实现高温超导约瑟夫森结器件的有前景方法。尽管已建立经验性的剂量-特性关系，但潜在的输运机制仍不明确。本研究详细探究了采用氦离子显微镜（HIM）制备的YBCO弱连接的输运特性，并基于具有扩散型金属中间层的SNS结理论，对观测到的行为给出了统一的唯象描述。我们证明，在宽温度范围内，临界电流$I_{\text{c}}$的温度依赖关系和$I_{\text{c}}R_{\text{n}}$乘积可由扩散型SNS结模型很好地描述。分析显示，观测到的$I_{\text{c}}$和$I_{\text{c}}R_{\text{n}}$的剂量依赖关系无法仅通过有效 Thouless 能量$E_{\text{T}}$的变化来解释。这种差异表明界面透明度降低、态密度减小，导致参与输运的有效导电通道数目减少。该解释也与观测到的$R_{\text{n}}$随辐照剂量呈指数增长的结果一致。这些结果为理解约瑟夫森输运以及指导氦离子辐照YBCO弱连接的结设计，提供了基于扩散的框架。
英文摘要
Fabrication of YBCO weak links by focused helium ion beam irradiation is a promising approach for realizing high-temperature superconducting Josephson junction devices. Although empirical dose-characteristic relationships have been established, the underlying transport mechanisms remain unclear. In this study, we perform a detailed investigation of the transport properties of YBCO weak links fabricated using a helium ion microscope (HIM) and provide a unified phenomenological description of the observed behavior based on the theory of SNS junctions with a diffusive metallic interlayer. We demonstrate that the temperature dependence of the critical current $I_{\mathrm{c}}$ and the $I_{\mathrm{c}}R_{\mathrm{n}}$ product are well described by diffusive SNS junction models over a wide temperature range. Analyses show that the observed dose dependences of $I_{\mathrm{c}}$ and $I_{\mathrm{c}}R_{\mathrm{n}}$ cannot be explained solely by variations in the effective Thouless energy $E_{\mathrm{T}}$. The discrepancy suggests reduced interface transparency and a reduction in the density of states, leading to a decrease in the effective number of conducting channels contributing to transport. This interpretation is also consistent with the observed exponential increase in $R_{\mathrm{n}}$ with irradiation dose. These results provide a diffusion-based framework for understanding Josephson transport and guiding junction design in helium-ion-irradiated YBCO weak links.
Comments11 pages, 7 figures
