Nickelate Superconductors: A Gateway to High-Temperature Superconductivity

The recent discovery of superconductivity in nickelate materials has generated significant excitement in the condensed matter physics community, representing the first new family of unconventional superconductors that share structural and electronic similarities with cuprate high-temperature superconductors since their discovery over three decades ago. This comprehensive review systematically examines the crystal and electronic structure, synthesis methods, physical properties, and current research status of nickelate superconductors. This paper analyzes the superconducting parameters, including critical temperature and upper critical field values reported across various nickelate systems, with particular emphasis on the infinite-layer nickelates (RNiO₂, R=rare earth) and the newly discovered bilayer La₃Ni₂O₇ under high pressure. Ultimately, this review concludes that while infinite-layer and pressure-induced bilayer nickelates offer a vital comparative platform for decoding unconventional superconductivity and strong electron correlations, the field is fundamentally bottlenecked by phase metastability and thin-film synthesis constraints. Overcoming these specific material challenges to enable ambient-pressure bulk superconductivity, coupled with systematic comparative studies against cuprates, constitutes the essential pathway for unveiling the universal mechanisms of high-temperature superconductivity.