Scientists at the Chinese Academy of Sciences' Institute of Physics (IOP) have created a practical, all-purpose, atomic-level manufacturing method known as vdW squeezing to produce 2D metals at the angstrom thickness limit. The study was published in the journal Nature.
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The rapid advancement of two-dimensional (2D) materials since the ground-breaking discovery of graphene in 2004 has sparked a new wave of basic research and technological innovation.
Most 2D materials are restricted to van der Waals (vdW) layered crystals, even though nearly 2,000 2D materials have been theoretically predicted and hundreds have been produced in lab settings.
Scientists have long been eager to create atomically thin 2D metals to broaden the family of 2D materials beyond vdW layered structures. These ultrathin 2D metals would also make the investigation of new physics and device architectures possible.
Numerous attempts have been made in recent years to create 2D metals, but they have not been successful in producing pristine, large-sized 2D metals at the atomically thin limit.
In the manufacturing process, pure metals are melted and compressed under high pressure between two rigid vdW anvils. The researchers used this technique to create a variety of atomically thin 2D metals, such as Bi (~6.3 Å), Sn (~5.8 Å), Pb (~7.5 Å), In (~8.4 Å), and Ga (~9.2 Å).
Two single-crystalline MoS2 monolayers grown epitaxially on sapphire make up the vdW anvils. For two reasons, the anvils are necessary to produce 2D metals. First, uniform 2D metal thickness on a large scale is guaranteed by the monolayer MoS2/sapphire's atomically flat, dangling-bond-free surface.
Second, 2D metals formed between the two anvils can approach their angstrom thickness limit because sapphire and monolayer MoS2 have high Young's moduli (>300 GPa), which enable them to withstand extreme pressures.
Complete encapsulation between two MoS2 monolayers stabilized the 2D metals produced using this method, guaranteeing non-bonded interfaces and environmental stability. This structure made device fabrication easier by providing access to their inherent transport properties, which were previously unattainable.
Electrical and spectroscopic measurements discovered excellent physical characteristics of monolayer Bi. These included new phonon modes, a strong field effect with p-type behavior, large nonlinear Hall conductivity, and significantly increased electrical conductivity.
This vdW squeezing atomic-level manufacturing method provides a flexible approach to creating various 2D metals while also enabling precise control over their thickness at the atomic level (e.g., monolayer, bilayer, or trilayer) by adjusting the squeezing pressure. This technique provides previously unattainable possibilities for exposing the unique layer-dependent characteristics of 2D metals.
According to Professor Guangyu Zhang, the study corresponding author from IOP, the vdW squeezing technique provides an efficient atomic-level method for producing 2D metal alloys, as well as amorphous and other 2D non-vdW compounds.
He also pointed out that this approach provides a “bright vision” for various new electronic, quantum, and photonic devices. He underlined that there is “plenty of room” for future growth in this emerging field of study.
Journal Reference:
Zhao, J., et al. (2025) Realization of 2D metals at the ångström thickness limit. Nature. doi.org/10.1038/s41586-025-08711-x.