A new method called vdW squeezing enables the creation of stable, atomically thin 2D metals, opening doors to advanced devices and fundamental discoveries in materials science.
Since the discovery of graphene in 2004, research into two-dimensional (2D) materials has advanced rapidly, opening new frontiers in both fundamental science and technological development. While nearly 2,000 2D materials have been theoretically predicted and hundreds successfully synthesized in laboratories, the vast majority are limited to van der Waals (vdW) layered crystals.
A major goal in the field has been the development of atomically thin 2D metals, which would significantly broaden the scope of 2D materials beyond vdW structures. These ultrathin metals could also unlock new physical phenomena and enable novel device architectures. Despite considerable effort in recent years, producing large-area, high-quality 2D metals at the atomic scale has remained a major challenge.
Breakthrough via vdW Squeezing
Now, however, researchers from the Institute of Physics (IOP) of the Chinese Academy of Sciences have developed a convenient, universal, atomic-level manufacturing technique—called vdW squeezing—for the production of 2D metals at the angstrom thickness limit. This study was recently published in Nature.
The manufacturing technique involves melting and squeezing pure metals between two rigid vdW anvils under high pressure. With this method, the researchers produced diverse atomically thin 2D metals, including Bi (~6.3 Å), Sn (~5.8 Å), Pb (~7.5 Å), In (~8.4 Å) and Ga (~9.2 Å).
Stability and Performance of 2D Metals
The vdW anvils consist of two single-crystalline MoS2 monolayers epitaxially grown on sapphire. The anvils are essential for producing 2D metals for two reasons. First, the atomically flat, dangling-bond-free surface of the monolayer MoS2/sapphire ensures uniform 2D metal thickness over a large scale. Second, the high Young’s modulus of both sapphire and monolayer MoS2 (> 300 GPa) allows them to withstand extreme pressures, enabling 2D metals formed between the two anvils to approach their angstrom thickness limit.
The 2D metals synthesized via this process were stabilized through complete encapsulation between two MoS2 monolayers, making them environmentally stable and ensuring non-bonded interfaces. This structure facilitated device fabrication by allowing access to their intrinsic transport properties, which were previously unavailable. Electrical and spectroscopic measurements of monolayer Bi revealed excellent physical properties, including significantly enhanced electrical conductivity, a strong field effect with p-type behavior, large nonlinear Hall conductivity, and new phonon modes.
Atomic Precision and Future Applications
This vdW squeezing, atomic-level manufacturing method not only offers a versatile approach to realizing various 2D metals but can also control the thickness of 2D metals with atomic precision (i.e., monolayer, bilayer, or trilayer) by controlling the squeezing pressure. This method offers extraordinary opportunities for revealing the exotic layer-dependent properties of 2D metals—something that was not possible before.
Prof. Guangyu Zhang from IOP, corresponding author of the study, said that the vdW squeezing technique offers an effective atomic-level method for manufacturing 2D metal alloys, as well as amorphous and other 2D non-vdW compounds. He also noted that this method outlines a “bright vision” for a broad range of emerging quantum, electronic, and photonic devices. He emphasized that there is “plenty of room” for this new research field to grow in the future.
Reference: “Realization of 2D metals at the ångström thickness limit” by Jiaojiao Zhao, Lu Li, Peixuan Li, Liyan Dai, Jingwei Dong, Lanying Zhou, Yizhe Wang, Peihang Zhang, Kunshan Ji, Yangkun Zhang, Hua Yu, Zheng Wei, Jiawei Li, Xiuzhen Li, Zhiheng Huang, Boxin Wang, Jieying Liu, Yutong Chen, Xingchao Zhang, Shuopei Wang, Na Li, Wei Yang, Dongxia Shi, Jinbo Pan, Shixuan Du, Luojun Du and Guangyu Zhang, 12 March 2025, Nature.
DOI: 10.1038/s41586-025-08711-x
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