SHENZHEN, May 22 (Xinhua) -- A Chinese research team has made a major advance in understanding high-temperature superconductivity, offering critical experimental evidence that sheds new light on its underlying mechanism.
The study, conducted by researchers from the University of Science and Technology of China (USTC) and the Southern University of Science and Technology (SUSTech), successfully observed a "nodeless superconducting gap" and "electron-boson coupling" in nickel oxide high-temperature superconducting thin films for the first time. The findings were recently published online in the journal Science.
According to Xue Qikun, an academician of the Chinese Academy of Sciences and a professor at SUSTech, the symmetry of the superconducting gap and the superconducting pairing mechanism are two key issues in high-temperature superconductivity research.
This symmetry determines whether the superconducting gap is uniform. In a superconductor, electrons must pair up to save energy, a process measured by the "superconducting gap." While traditional superconductors possess a fully uniform gap free of "nodes" (points where the gap is zero), copper-based superconductors are thought to exhibit nodes in specific directions.
By studying new nickel-based films, the team discovered their superconducting gap is nodeless. This suggests that nickel-based and copper-based superconductors may function under different physical rules.
The team also uncovered how these electrons may manage to pair up. Since electrons naturally repel each other, they usually need a "matchmaker" to bring them together. The researchers found a unique "fingerprint" signal in the energy data, suggesting that mediating bosons possibly act as this go-between to facilitate the pairing in nickel-based materials.
Nickel-based superconductivity research is currently a cutting‑edge hotspot in the global scientific community, marked by extreme technical challenges in material preparation and equipment development.
Prior to this discovery, the team had already achieved a series of systematic advances in material synthesis and electronic structure studies, including the development of atomic-level preparation techniques for complex oxides, paving the way for this study.
"This is a key step in quantum matter research," Xue said. "It reflects China's deepening role in frontier physics and its growing contribution to the global effort to understand high-temperature superconductivity." ■
