Host: Hanghui Chen, NYU Shanghai
Abstract:
The high-temperature superconductivity discovered recently in the Ruddlesden-Popper (RP) phase multilayer superconductors has aroused great research interests. In this talk, I will first make a brief introduction over the experimental progress, and then report our series of works adopting the strong-coupling picture for this family. We propose that the SC of La3Ni2O7 under high pressure is carried by the dx2-y2 orbital, and that the dz2 orbital also plays an important role through the Hund’s rule coupling. Based on this viewpoint, we construct the dx2-y2 orbital bilayer t-J-J_\perp model for La3Ni2O7. With this model, we can naturally understand why HTSC arises under HP or in the film at AP. Recently, using this model, we provide a unified understanding toward the experiments which control Tc through tuning enviroment conditions, establishing this model as the minimal model regarding the pairing mechanism in the bilayer nickelates. We also predict possible ways to enhance the Tc, with part of them verified by experiments.
Biography:
Fan Yang is a professor of physics in Beijing Institute of Technology. He was graduated from Peking University in 2002, where he obtained the Ph. D degree. After two years' post doctoral research in the Institute of Advanced Study in Tsinghua University, Fan Yang joined the Physics department of Beijing Institute of Technology. He was promoted as full professor in 2013. Fan Yang's research area is condensed-matter physics, with a focus on theory of strongly-correlated electronic systems and superconductivity. He has made contributions in the research field of cuprates, the iron-based superconductivity, the quantum spin liquid, the twisted bilayer graphene, and the electronic states in the quasicrystals. Fan Yang's recent focus is the nickle-based superconductivity. He has published about 100 papers, with citation over 4000 times.
Seminar by the NYU-ECNU Institute of Physics at NYU Shanghai