High-Temperature Superconducting YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ Josephson Junction Fabricated with a Focused Helium Ion Beam
Ziwen Chen1,2,3, Yulong Li1,2,3, Rui Zhu4, Jun Xu4, Tiequan Xu1,2,3, Dali Yin1,2,3, Xinwei Cai1,2,3, Yue Wang1,2,3, Jianming Lu1,2,3, Yan Zhang1,2,3*, and Ping Ma1,2,3*
1Applied Superconductivity Research Center, Peking University, Beijing 100871, China 2State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Peking University, Beijing 100871, China 3School of Physics, Peking University, Beijing 100871, China 4Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
Abstract：As a newly developed method for fabricating Josephson junctions, a focused helium ion beam has the advantage of producing reliable and reproducible junctions. We fabricated Josephson junctions with a focused helium ion beam on our 50 nm YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ (YBCO) thin films. We focused on the junction with irradiation doses ranging from 100 to 300 ions/nm and demonstrated that the junction barrier can be modulated by the ion dose and that within this dose range, the junctions behave like superconductor–normal-conductor–superconductor junctions. The measurements of the $I$–$V$ characteristics, Fraunhofer diffraction pattern, and Shapiro steps of the junctions clearly show AC and DC Josephson effects. Our findings demonstrate high reproducibility of junction fabrication using a focused helium ion beam and suggest that commercial devices based on this nanotechnology could operate at liquid nitrogen temperatures.
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2022, Vol. 39 
