Printable two-dimensional superconducting monolayers

• Published in: Nature materials 2021-02, Vol.20 (2), p.181-187
• Main Authors: Li, Jing, Song, Peng, Zhao, Jinpei, Vaklinova, Kristina, Zhao, Xiaoxu, Li, Zejun, Qiu, Zhizhan, Wang, Zihao, Lin, Li, Zhao, Meng, Herng, Tun Seng, Zuo, Yuxin, Jonhson, Win, Yu, Wei, Hai, Xiao, Lyu, Pin, Xu, Haomin, Yang, Huimin, Chen, Cheng, Pennycook, Stephen J., Ding, Jun, Teng, Jinghua, Castro Neto, A. H., Novoselov, Kostya S., Lu, Jiong
• Format: Article
• Language: English
• Subjects: 142/136; 639/301/119/1003; 639/301/357/1018; Ammonium; Biomaterials; Cations; Chemistry and Materials Science; Condensed Matter Physics; Critical current (superconductivity); Critical field (superconductivity); Crystal structure; Crystallinity; Electrochemistry; Exfoliation; Fabrication; Graphene; Heterostructures; Inks; Interface stability; Interfacial properties; Ising model; Magnetic fields; Magnetic flux; Magnetic properties; Materials Science; Microscopy; Molecular beam epitaxy; Monolayers; Morphology; Nanotechnology; Optical and Electronic Materials; Oxidation; Phase transitions; Single crystals; Solvents; Superconductivity; Three dimensional composites
• ISSN: 1476-1122; 1476-4660
• DOI: 10.1038/s41563-020-00831-1

Two-dimensional superconductor (2DSC) monolayers with non-centrosymmetry exhibit unconventional Ising pair superconductivity and an enhanced upper critical field beyond the Pauli paramagnetic limit, driving intense research interest. However, they are often susceptible to structural disorder and environmental oxidation, which destroy electronic coherence and provide technical challenges in the creation of artificial van der Waals heterostructures (vdWHs) for devices. Herein, we report a general and scalable synthesis of highly crystalline 2DSC monolayers via a mild electrochemical exfoliation method using flexible organic ammonium cations solvated with neutral solvent molecules as co-intercalants. Using NbSe 2 as a model system, we achieved a high yield (>75%) of large-sized single-crystal monolayers up to 300 µm. The as-fabricated, twisted NbSe 2 vdWHs demonstrate high stability, good interfacial properties and a critical current that is modulated by magnetic field when one flux quantum fits to an integer number of moiré cells. Additionally, formulated 2DSC inks can be exploited to fabricate wafer-scale 2D superconducting wire arrays and three-dimensional superconducting composites with desirable morphologies. A mild electrochemical exfoliation method has been developed to obtain large-size two-dimensional superconductor monolayers with high crystallinity and production yield, which enables the easy fabrication of twisted van der Waals heterostructures and printed films.