The discovery and research progress of the nickelate superconductors

The discovery of the nickelate superconductors has motivated the search for new unconventional superconductors, analogous to cuprates and spurred the revolving interest on the mechanism of high-temperature superconductivity, with the focus on the relationship between the crystal structure and the detailed electronic structure. This article briefly reviews the discovery of the nickelate superconductors with the infinite-layer structure, the on-going experimental efforts, and the evolving understanding of the physics on this new superconducting system. It also discusses the open questions regarding (but not limited to) the exploration of a whole family of nickelate superconductors, materials growth issues, physics problems, and immediate research topics/directions in this new field.