Presentation Information
[ED6-03]Temperature and Dose Dependence of Helium Ion Microscopy-Fabricated YBCO Josephson Junctions
*Tetsuro Misawa1, Shinichi Ogawa1, Yukinori Morita1, Shigeyuki Ishida1, Hiroshi Eisaki1, Chiharu Urano (1. National Institute of Advanced Industrial Science and Technology (AIST) (Japan))
Keywords:
HTS,Josephson junction,Helium ion microscopy,Critical current,IcRn,Shapiro steps
Recent advances in fabrication techniques have enabled the realization of Josephson junctions in high-Tc superconductor (HTS) films by irradiating them with a finely focused helium ion beam of sub-nanometer diameter [1]. In this approach, Josephson junctions are “directly written” onto HTS films, and their properties can be precisely tuned by controlling the helium ion irradiation dose [2]. This capability has attracted increasing attention for applications such as nano-SQUIDs, terahertz devices, and superconducting digital circuits.
Since the optimal junction characteristics depend on the operating temperature, it is essential to evaluate the HIM-fabricated junctions with different ion doses across a broad temperature range. Here, we investigated HIM-fabricated YBCO Josephson junctions over temperatures from 3.1 K to 70 K using a pulse-tube cryocooler-based measurement system. The irradiation doses ranged from 230 to 382 ions/nm, with an acceleration voltage of 30 kV. The measured current–voltage characteristics were well described by the resistively shunted junction (RSJ) model. RSJ model fitting indicated minimal excess currents across all measurement temperatures, which enabled accurate determination of the critical current Ic and normal resistance Rn. These parameters also allowed quantitative reproduction of Shapiro steps under 10–20 GHz microwave irradiation, confirming the validity of the RSJ description of the junctions. Those measurements with varying helium ion doses revealed quantitatively consistent dependencies of YBCO Josephson junction properties on both temperature and dose. These results provide practical design guidelines for fabricating YBCO Josephson junctions with tailored characteristics for specific operating conditions, supporting their application for a wide range of superconducting technologies.
References
1) S. A. Cybart et al., “Nano Josephson superconducting tunnel junctions in YBa2Cu3O7-δ directly patterned with a focused helium ion beam,” Nature Nanotechnology, vol. 10, no. 7, pp. 598–602
2) Ogawa et al., “Formation of Lateral-Type High-Tc Superconductor Josephson Junction by Helium Ion Microscopy,” 2024 IEEE International Interconnect Technology Conference (IITC), San Jose, CA, USA, 2024, pp. 1-3, doi: 10.1109/IITC61274.2024.10732494.
Acknowledgment
This work was supported by JSPS KAKENHI Grant Number 20H02631 and JP23K26152. This work was also supported by "Advanced Research Infrastructure for Materials and Nanotechnology in Japan (ARIM)" of the Ministry of Education, Culture, Sports, Science and Technology (MEXT). Grant Number JPMXP1223AT0379.
Since the optimal junction characteristics depend on the operating temperature, it is essential to evaluate the HIM-fabricated junctions with different ion doses across a broad temperature range. Here, we investigated HIM-fabricated YBCO Josephson junctions over temperatures from 3.1 K to 70 K using a pulse-tube cryocooler-based measurement system. The irradiation doses ranged from 230 to 382 ions/nm, with an acceleration voltage of 30 kV. The measured current–voltage characteristics were well described by the resistively shunted junction (RSJ) model. RSJ model fitting indicated minimal excess currents across all measurement temperatures, which enabled accurate determination of the critical current Ic and normal resistance Rn. These parameters also allowed quantitative reproduction of Shapiro steps under 10–20 GHz microwave irradiation, confirming the validity of the RSJ description of the junctions. Those measurements with varying helium ion doses revealed quantitatively consistent dependencies of YBCO Josephson junction properties on both temperature and dose. These results provide practical design guidelines for fabricating YBCO Josephson junctions with tailored characteristics for specific operating conditions, supporting their application for a wide range of superconducting technologies.
References
1) S. A. Cybart et al., “Nano Josephson superconducting tunnel junctions in YBa2Cu3O7-δ directly patterned with a focused helium ion beam,” Nature Nanotechnology, vol. 10, no. 7, pp. 598–602
2) Ogawa et al., “Formation of Lateral-Type High-Tc Superconductor Josephson Junction by Helium Ion Microscopy,” 2024 IEEE International Interconnect Technology Conference (IITC), San Jose, CA, USA, 2024, pp. 1-3, doi: 10.1109/IITC61274.2024.10732494.
Acknowledgment
This work was supported by JSPS KAKENHI Grant Number 20H02631 and JP23K26152. This work was also supported by "Advanced Research Infrastructure for Materials and Nanotechnology in Japan (ARIM)" of the Ministry of Education, Culture, Sports, Science and Technology (MEXT). Grant Number JPMXP1223AT0379.