Brevoord J M, Wielens D H, Lankhorst M, Díez-Mérida J, Huang Y, Li C, Brinkman A
MESA+ Institute for Nanotechnology, University of Twente, The Netherlands.
Van der Waals-Zeeman Institute, IoP, University of Amsterdam, The Netherlands.
Nanotechnology. 2021 Aug 2;32(43). doi: 10.1088/1361-6528/ac14e8.
Fractional charges can be induced by magnetic fluxes at the interface between a topological insulator (TI) and a type-II superconductor due to axion electrodynamics. In a Josephson junction array with a hole in the middle, these electronic states can have phase interference in an applied magnetic field with4×2πperiod, in addition to the 2interference of the Cooper pairs. Here, we test an experimental configuration for probing the fractional charge and report the observation of phase interference effect in superconducting arrays with a hole in the middle in both Au- and TI-based devices. Our numerical simulations based on resistive shunted capacitive junction model are in good agreement with the experimental results. However, no clear sign of an axion charge-related interference effect was observed. We will discuss possible reasons and perspectives for future experiments.
由于轴子电动力学，在拓扑绝缘体（TI）与II型超导体的界面处，磁通量可诱导出分数电荷。在中间有一个孔的约瑟夫森结阵列中，除了库珀对的2π干涉外，这些电子态在4×2π周期的外加磁场中会发生相位干涉。在此，我们测试了一种用于探测分数电荷的实验配置，并报告了在基于金和TI的器件中，对中间有孔的超导阵列中相位干涉效应的观测结果。我们基于电阻分流电容结模型的数值模拟与实验结果吻合良好。然而，未观察到与轴子电荷相关的干涉效应的明显迹象。我们将讨论可能的原因以及未来实验的前景。
