What is the 'thinnest thing'? We often use the phrase 'as thin as cicada wings' to describe a material that is extremely thin and light. However, in the microscopic world, there are still materials as thin as tens of thousands of parts of cicada wings, which are two-dimensional materials. The Physical World (sponsored by the British Physical Society) recently released the list of "Top Ten Scientific Breakthroughs in 2025", and the "First 2D Metal Preparation" achievement led by Zhang Guangyu from the Institute of Physics of the Chinese Academy of Sciences/National Research Center for Condensed Matter Physics was successfully selected. This is the 7th time that China's leading research has won this honor since the establishment of the list in 2009, and it is also the only Chinese achievement selected this year. Together with major international breakthroughs such as clues to the origin of asteroid life and molecular superfluidity phenomena, it ranks among the top. Since graphene was discovered in 2004 and ushered in a new era of two-dimensional materials, scientists worldwide have prepared hundreds of two-dimensional materials, with theoretical predictions approaching 2000. However, these materials are limited to layered systems - structures similar to "thousand layered cakes" that can be obtained as monolayers through mechanical exfoliation and other methods. The metal elements, which account for about 80% of the periodic table, are difficult to separate like "compressed biscuits" due to their non layered structure, strong metal bonds, and high symmetry. This has long been considered an "impossible task" by the academic community to obtain atomically thin two-dimensional metals, and has become a major gap in the field of two-dimensional materials. To overcome this challenge, Zhang Guangyu's team has been working on it for many years, creating relevant technologies and utilizing the team's independently developed atomic level flat single-layer molybdenum disulfide anvil for extrusion. They have achieved universal preparation of two-dimensional metals at the Emmy level (1 Emmy equals 0.1 nanometers) ultimate thickness, successfully obtaining five types of two-dimensional metals: bismuth (6.3 Emmy), tin (5.8 Emmy), lead (7.5 Emmy), indium (8.4 Emmy), and gallium (9.2 Emmy) - the thickness of these materials is only one 200000 times the diameter of a human hair and one millionth the thickness of A4 paper. The two-dimensional metal prepared through this technological breakthrough has good environmental stability and no performance degradation in over a year of experimental testing, laying the foundation for exploring the intrinsic properties of the material. "This breakthrough not only fills the key gap in the two-dimensional material family, but also opens up a new research field." Du Luojun, the co corresponding author of the paper and the distinguished researcher of the Institute of Physics of the Chinese Academy of Sciences, pointed out that two-dimensional metals are expected to generate high-temperature quantum Hall effect, two-dimensional superconductivity and other macroscopic quantum phenomena, providing core materials for technological innovation such as low-power transistors, high-frequency devices, ultra sensitive detection, etc. In his view, the five two-dimensional metals currently achieved are only the "tip of the iceberg", and with the addition of binary and multicomponent alloys, there are still tens of thousands of two-dimensional metal materials to be explored in the future, leaving a vast space for this field. The selected achievements of the "Top 10 Scientific Breakthroughs of the Year" in Physics World must meet the four core criteria of "significant scientific significance, pushing the boundaries of knowledge, closely integrating theory and experiment, and attracting widespread attention from physicists worldwide". This achievement, with its disruptive contribution to materials science, universal value of innovative technology, and broad application prospects, has successfully entered the list, marking China's international leading position in the field of two-dimensional material atomic manufacturing. (New Society)