Time：

2021-10-22 10：00am

Adress：

Office Building Room 306

Speaker

Professor Hai-QingLin

Abstract:

In this talk, Ireport our efforts on understanding the mechanism of high-temperaturesuperconductivity in cuprates. By considering the widely accepted dispersionof electronic structure, we developed an extended interlayer coupling modelfor layered d-wave cuprate superconductors . We showed the change of themaximum critical temperature Tc from homologous series to series isdetermined by the next-nearest-neighboring hopping, while the difference ofthe maximum Tc among the compounds in the same homologous series iscontrolled by the interlayer pairing strength. These trends turn out to bevalid when the model is extended to the phonon-mediated superconductivity .We further found that the dependence of both Tc and the oxygen isotopeexponent on the doping level, number of CuO2 layers, and cation disorder inthe mercury-, bismuth-, and thallium-based family can be well reproducedwithin one single theoretical framework. Assuming the effective attractiveinteraction, the hole concentration, and phonon cutoff frequency as intrinsicpressure variables, we also found that the theoretical model accounts wellfor the pressure dependence of Tc in Y-Ba-Cu-O system as well as in otherhomologous families . Our recent experimental results on the Tc evolutionwith pressure in optimally doped Tl- and Bi-based compounds provide thestrong support for the importance of the electron-phonon coupling forsuperconductivity in high-Tc cuprates.