Title：Computing spin fluctuational coupling in unconventional superconductors from (almost) first principles
Speaker：Prof. Sergey Savrasov (Department of Physics and Astronomy, University of California, Davis, USA)
Date：2024/03/15 (Fri.)
Time：14:20
Place：R307 Seminar Room, 3F, Cosmology Hall, NTU
 
Abstract：
I will overview our recent works on diagonalizing BCS gap equation where the matrix elements of scattering between the Cooper pairs come from first principle evaluation of the RPA type expression based on density functional derived band structures and wave functions. This approach has an advantage of not involving tight-binding approximations widely employed in the past to calculate spin fluctuations in high Tc cuprates and other unconventional superconductors. Superconducting energy gaps, and material specific spin fluctuational coupling constants will be evaluated for doped HgBa₂CuO₄, YBa₂Cu₃O₇, La₂CuO₄ as well as most recently discovered nickelate La₃Ni₂O₇. Perspective will be given whether such theory can track material dependence of Tc similar to successes of electron-phonon theory in first principle description of conventional superconductors.