Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Emergent ferromagnetism with superconductivity in Fe(Te,Se) van der Waals Josephson junctions



Gang Qiu, Hung-Yu Hu, Lunhui Hu, Huairuo Zhang, Chi-Yen Chen, Yanfeng Lyu, Christopher Eckberg, Peng Deng, Sergiy Krylyuk, Albert Davydov, Ruixing Zhang, Kang Wang


Ferromagnetism and superconductivity are two key ingredients for topological superconductors, which can serve as building blocks of fault-tolerant quantum computers. Adversely, ferromagnetism and superconductivity are typically also two hostile orderings competing to align spins in different configurations, and thus making the material design and experimental implementation extremely challenging. A single material platform with concurrent ferromagnetism and superconductivity is actively pursued. In this paper, we fabricate van der Waals Josephson junctions made with iron-based superconductor Fe(Te,Se), and report the global device-level transport signatures of interfacial ferromagnetism emerging with superconducting states for the first time. Magnetic hysteresis in the junction resistance is observed only below the superconducting critical temperature, suggesting an inherent correlation between ferromagnetic and superconducting order parameters. The 0-π phase mixing in the Fraunhofer patterns pinpoints the ferromagnetism on the junction interface. More importantly, a stochastic field-free superconducting diode effect was observed in Josephson junction devices, with a significant diode efficiency up to 10%, which unambiguously confirms the spontaneous time-reversal symmetry breaking. Our work demonstrates a new way to search for topological superconductivity in iron-based superconductors for future high Tc fault-tolerant qubit implementations from a device perspective.
Nature Communications


van der Waals materials, Josephson junction, superconductivity


Qiu, G. , Hu, H. , Hu, L. , Zhang, H. , Chen, C. , Lyu, Y. , Eckberg, C. , Deng, P. , Krylyuk, S. , Davydov, A. , Zhang, R. and Wang, K. (2023), Emergent ferromagnetism with superconductivity in Fe(Te,Se) van der Waals Josephson junctions, Nature Communications, [online],, (Accessed May 23, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created October 23, 2023, Updated October 24, 2023