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

Published

October 23, 2023

Author(s)

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

Abstract

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.

Citation

Nature Communications

Volume

14

Pub Type

Journals

Download Paper

https://doi.org/10.1038/s41467-023-42447-4

Local Download

Keywords

van der Waals materials, Josephson junction, superconductivity

Citation

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], https://doi.org/10.1038/s41467-023-42447-4, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=936595 (Accessed October 10, 2025)