中国物理B ›› 2024, Vol. 33 ›› Issue (4): 47405-047405.doi: 10.1088/1674-1056/ad21f7

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Co-doped BaFe2As2 Josephson junction fabricated with a focused helium ion beam

Ziwen Chen(陈紫雯)1,2,3,4, Yan Zhang(张焱)1,2,3,4,†, Ping Ma(马平)1,2,3,4,‡, Zhongtang Xu(徐中堂)5,§, Yulong Li(李宇龙)1,2,3,4, Yue Wang(王越)1,2,3,4, Jianming Lu(路建明)1,2,3,4, Yanwei Ma(马衍伟)5, and Zizhao Gan(甘子钊)1,2,3,4   

  1. 1 Applied Superconductivity Research Center, Peking University, Beijing 100871, China;
    2 State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Peking University, Beijing 100871, China;
    3 Institute of Condensed Matter Physics, School of Physics, Peking University, Beijing 100871, China;
    4 Yangtze Delta Institute of Optoelectronics, Peking University, Beijing 100871, China;
    5 Key Laboratory of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China
  • 收稿日期:2023-12-29 修回日期:2024-01-14 接受日期:2024-01-24 出版日期:2024-03-19 发布日期:2024-03-19
  • 通讯作者: Yan Zhang, Ping Ma, Zhongtang Xu E-mail:zhang_yan@pku.edu.cn;maping@pku.edu.cn;ztxu@mail.iee.ac.cn
  • 基金资助:
    Project supported by the National Key Research and Development Program of China (Grant Nos. 2020YFF01014706 and 2017YFC0601901) and the National Natural Science Foundation of China (Grant Nos. 61571019 and 52177026). The authors would like to acknowledge the valuable contributions of Lifeng Tian, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, for his help in use of helium ion microscope; and Ziqing Chen for the artistic drawing of the Ba122:Co junction fabricated by a focused helium ion beam.

Co-doped BaFe2As2 Josephson junction fabricated with a focused helium ion beam

Ziwen Chen(陈紫雯)1,2,3,4, Yan Zhang(张焱)1,2,3,4,†, Ping Ma(马平)1,2,3,4,‡, Zhongtang Xu(徐中堂)5,§, Yulong Li(李宇龙)1,2,3,4, Yue Wang(王越)1,2,3,4, Jianming Lu(路建明)1,2,3,4, Yanwei Ma(马衍伟)5, and Zizhao Gan(甘子钊)1,2,3,4   

  1. 1 Applied Superconductivity Research Center, Peking University, Beijing 100871, China;
    2 State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Peking University, Beijing 100871, China;
    3 Institute of Condensed Matter Physics, School of Physics, Peking University, Beijing 100871, China;
    4 Yangtze Delta Institute of Optoelectronics, Peking University, Beijing 100871, China;
    5 Key Laboratory of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2023-12-29 Revised:2024-01-14 Accepted:2024-01-24 Online:2024-03-19 Published:2024-03-19
  • Contact: Yan Zhang, Ping Ma, Zhongtang Xu E-mail:zhang_yan@pku.edu.cn;maping@pku.edu.cn;ztxu@mail.iee.ac.cn
  • Supported by:
    Project supported by the National Key Research and Development Program of China (Grant Nos. 2020YFF01014706 and 2017YFC0601901) and the National Natural Science Foundation of China (Grant Nos. 61571019 and 52177026). The authors would like to acknowledge the valuable contributions of Lifeng Tian, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, for his help in use of helium ion microscope; and Ziqing Chen for the artistic drawing of the Ba122:Co junction fabricated by a focused helium ion beam.

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摘要： Josephson junction plays a key role not only in studying the basic physics of unconventional iron-based superconductors but also in realizing practical application of thin-film based devices, therefore the preparation of high-quality iron pnictide Josephson junctions is of great importance. In this work, we have successfully fabricated Josephson junctions from Co-doped BaFe2As2 thin films using a direct junction fabrication technique which utilizes high energy focused helium ion beam (FHIB). The electrical transport properties were investigated for junctions fabricated with various He+ irradiation doses. The junctions show sharp superconducting transition around 24 K with a narrow transition width of 2.5 K, and a dose correlated foot-structure resistance which corresponds to the effective tuning of junction properties by He+ irradiation. Significant Jc suppression by more than two orders of magnitude can be achieved by increasing the He+ irradiation dose, which is advantageous for the realization of low noise ion pnictide thin film devices. Clear Shapiro steps are observed under 10 GHz microwave irradiation. The above results demonstrate the successful fabrication of high quality and controllable Co-doped BaFe2As2 Josephson junction with high reproducibility using the FHIB technique, laying the foundation for future investigating the mechanism of iron-based superconductors, and also the further implementation in various superconducting electronic devices.

关键词: focused helium ion beam, Co doped BaFe2As2, Josephson junction

Abstract: Josephson junction plays a key role not only in studying the basic physics of unconventional iron-based superconductors but also in realizing practical application of thin-film based devices, therefore the preparation of high-quality iron pnictide Josephson junctions is of great importance. In this work, we have successfully fabricated Josephson junctions from Co-doped BaFe2As2 thin films using a direct junction fabrication technique which utilizes high energy focused helium ion beam (FHIB). The electrical transport properties were investigated for junctions fabricated with various He+ irradiation doses. The junctions show sharp superconducting transition around 24 K with a narrow transition width of 2.5 K, and a dose correlated foot-structure resistance which corresponds to the effective tuning of junction properties by He+ irradiation. Significant Jc suppression by more than two orders of magnitude can be achieved by increasing the He+ irradiation dose, which is advantageous for the realization of low noise ion pnictide thin film devices. Clear Shapiro steps are observed under 10 GHz microwave irradiation. The above results demonstrate the successful fabrication of high quality and controllable Co-doped BaFe2As2 Josephson junction with high reproducibility using the FHIB technique, laying the foundation for future investigating the mechanism of iron-based superconductors, and also the further implementation in various superconducting electronic devices.

Key words: focused helium ion beam, Co doped BaFe2As2, Josephson junction

中图分类号:  (Pnictides and chalcogenides)

  • 74.70.Xa
85.25.Cp (Josephson devices) 07.78.+s (Electron, positron, and ion microscopes; electron diffractometers) 03.75.Lm (Tunneling, Josephson effect, Bose-Einstein condensates in periodic potentials, solitons, vortices, and topological excitations)