Since the discovery of high-temperature superconducting copper oxides, the study of their mechanism and the synthesis of new high-temperature superconducting materials have been the focus of researchers. The purpose is to continuously raise the superconducting transition temperature (Tc), to improve the superconducting properties, and to establish a suitable material basis for large-scale applications, including the search for copper-oxide-like high-temperature superconducting materials, such as nickel oxide.
However, after more than 30 years of exploration, when many scholars tend to believe that superconductivity is impossible in nickel oxide system, Professor Danfeng Li and Stanford University experimental team reported the discovery of Nd0.8Sr0.2NiO2 nickel oxide thin film superconductor for the first time in the world in 2019, which immediately aroused strong repercussions in the field of superconductivity research. It has then opened an upsurge in the research of nickel oxide superconductivity.
The research was published in Nature. Professor Yi Cui, as a collaborator, recalled the submission process and told us that "the paper was basically accepted in only 7 days after submission." As introduced in the article, Li took a very different and creative approach- they combined the atomic-scale synthesis of nickelates using thin-film growth techniques with novel soft chemistry topotactic reactions to synthesize the doped superconducting infinite layer nickelate system and later on found the superconducting phase diagram of the system. The implications of the work are manifold, ranging from presenting a new manifestation of unconventional superconductivity, providing a first direct example to compare and contrast with cuprates and deduce what features are universal, and of course to motivating a vast materials exploration.
After graduating from the University of Geneva, Li once worked as a postdoctoral researcher in the University of Geneva and Stanford University. Now Li has joined the City University of Hong Kong as an assistant professor. His research direction mainly focuses on superconducting materials and superconductivity, especially high-temperature superconductivity in oxide films and heterojunction structures, research on two-dimensional superconductivity and interface superconductivity, with the hope to find new superconducting material systems.
