Vlasko-Vlasov Vitalii K, Divan Ralu, Rosenmann Daniel, Welp Ulrich, Glatz Andreas, Kwok Wai-Kwong
Materials Science Division, Argonne National Laboratory, Argonne, IL, 60439, USA.
Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL, 60439, USA.
Sci Rep. 2023 Aug 3;13(1):12601. doi: 10.1038/s41598-023-39733-y.
We study the magnetic field response of millimeter scale fractal Sierpinski gaskets (SG) assembled of superconducting equilateral triangular patches. Directly imaged quantitative induction maps reveal hierarchical periodic filling of enclosed void areas with multiquanta magnetic flux, which jumps inside the voids in repeating bundles of individual flux quanta Φ. The number N of entering flux quanta in different triangular voids of the SG is proportional to the linear size s of the void, while the field periodicity of flux jumps varies as 1/s. We explain this behavior by modeling the triangular voids in the SG with effective superconducting rings and by calculating their response following the London analysis of persistent currents, J, induced by the applied field H and by the entering flux. With changing H, J reaches a critical value in the vertex joints that connect the triangular superconducting patches and allows the giant flux jumps into the SG voids through phase slips or multiple Abrikosov vortex transfer across the vertices. The unique flux behavior in superconducting SG patterns, may be used to design tunable low-loss resonators with multi-line high-frequency spectrum for microwave technologies.
我们研究了由超导等边三角形贴片组装而成的毫米级分形谢尔宾斯基垫片（SG）的磁场响应。直接成像的定量感应图揭示了封闭空隙区域被多量子磁通量分层周期性填充，这些磁通量在空隙内以单个磁通量子Φ的重复束状形式跳跃。SG不同三角形空隙中进入的磁通量子数N与空隙的线性尺寸s成正比，而磁通跳跃的场周期性随1/s变化。我们通过用有效的超导环对SG中的三角形空隙进行建模，并根据伦敦对由外加场H和进入的磁通感应的持续电流J的分析来计算其响应，从而解释了这种行为。随着H的变化，J在连接三角形超导贴片的顶点接头处达到临界值，并允许通过相位滑移或多个阿布里科索夫涡旋穿过顶点转移，使巨大的磁通跳跃到SG空隙中。超导SG图案中独特的磁通行为可用于设计具有多线高频频谱的可调低损耗谐振器，用于微波技术。
