Van der Waals ferromagnetic Josephson junctions

Linfeng Ai; Enze Zhang; Jinshan Yang; Xiaoyi Xie; Yunkun Yang; Zehao Jia; Yuda Zhang; Shanshan Liu; Zihan Li; Pengliang Leng; Xiangyu Cao; Xingdan Sun; Tongyao Zhang; Xufeng Kou; Zheng Han; Faxian Xiu; Shaoming Dong

doi:10.1038/s41467-021-26946-w

Van der Waals ferromagnetic Josephson junctions

Nat Commun. 2021 Nov 12;12(1):6580. doi: 10.1038/s41467-021-26946-w.

Authors

Linfeng Ai^#^{1

2}, Enze Zhang^#¹, Jinshan Yang^#³, Xiaoyi Xie^{1

2}, Yunkun Yang¹, Zehao Jia^{1

2}, Yuda Zhang^{1

2}, Shanshan Liu¹, Zihan Li¹, Pengliang Leng^{1

2}, Xiangyu Cao^{1

2}, Xingdan Sun⁴, Tongyao Zhang⁵, Xufeng Kou⁶, Zheng Han^{4

5}, Faxian Xiu^{7

8

9

10}, Shaoming Dong¹¹

Affiliations

¹ State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China.
² Shanghai Qi Zhi Institute, 41th Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, 200232, Shanghai, China.
³ State Key Laboratory of High Performance Ceramics & Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 200050, Shanghai, China.
⁴ Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 110016, Shenyang, China.
⁵ State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, 030006, Taiyuan, China.
⁶ School of Information Science and Technology, ShanghaiTech University, 201210, Shanghai, China.
⁷ State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China. Faxian@fudan.edu.cn.
⁸ Shanghai Qi Zhi Institute, 41th Floor, AI Tower, No. 701 Yunjin Road, Xuhui District, 200232, Shanghai, China. Faxian@fudan.edu.cn.
⁹ Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, 200433, Shanghai, China. Faxian@fudan.edu.cn.
¹⁰ Shanghai Research Center for Quantum Sciences, 201315, Shanghai, China. Faxian@fudan.edu.cn.
¹¹ State Key Laboratory of High Performance Ceramics & Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 200050, Shanghai, China. smdong@mail.sic.ac.cn.

^# Contributed equally.

Abstract

Superconductor-ferromagnet interfaces in two-dimensional heterostructures present a unique opportunity to study the interplay between superconductivity and ferromagnetism. The realization of such nanoscale heterostructures in van der Waals (vdW) crystals remains largely unexplored due to the challenge of making atomically-sharp interfaces from their layered structures. Here, we build a vdW ferromagnetic Josephson junction (JJ) by inserting a few-layer ferromagnetic insulator Cr₂Ge₂Te₆ into two layers of superconductor NbSe₂. The critical current and corresponding junction resistance exhibit a hysteretic and oscillatory behavior against in-plane magnetic fields, manifesting itself as a strong Josephson coupling state. Also, we observe a central minimum of critical current in some JJ devices as well as a nontrivial phase shift in SQUID structures, evidencing the coexistence of 0 and π phase in the junction region. Our study paves the way to exploring sensitive probes of weak magnetism and multifunctional building-blocks for phase-related superconducting circuits using vdW heterostructures.

Abstract

Grants and funding