Correlation-enhanced electron-phonon interaction in oxide superconductors from linear-response GW perturbation theory

Abstract:

Accurate and practical ab initio treatment of electron-phonon (e-ph) coupling is essential to the understanding of many condensed-matter phenomena. In this talk, I will present a new ab initio linear-response method named GW perturbation theory (GWPT) that computes the e-ph interaction with the inclusion of the GW nonlocal, energy-dependent self-energy effects [1]. GWPT goes beyond the commonly used density-functional perturbation theory (DFPT), which is inadequate in some materials where correlation effects are non-negligible. We first demonstrate the capability of GWPT by showing that the e-ph coupling in Ba1-xKxBiO3 is significantly enhanced by many-electron correlations, strong enough to explain its high superconducting Tc of 32 K [1]. Secondly, using full GW-level anisotropic Eliashberg equation calculations, we predict that the recently discovered infinite-layer nickelate superconductor Nd1-xSrxNiO2 hosts a strong phonon-mediate two-gap s-wave superconductivity, explaining some intriguing experimental observations [2]. Thirdly, we study the ubiquitous 70-meV dispersion kink in cuprates observed in angle-resolved photoemission experiments, and show that the correlation-enhanced e-ph interaction in La2-xSrxCuO4 gives rise to strong nodal kinks and their temperature and doping dependence in quantitative agreement with experiments [3].

[1] Z. Li, G. Antonius, M. Wu, F. da Jornada, and S. G. Louie, Phys. Rev. Lett. 122, 186402 (2019).

[2] Z. Li and S. G. Louie, arXiv:2210.12819 (2022).

[3] Z. Li, M. Wu, Y.-H. Chan, and S. G. Louie, Phys. Rev. Lett. 126, 146401 (2021).

Bio:

Dr. Zhenglu Li joined the Viterbi School of Engineering at the University of Southern California in January 2023 as an Assistant Professor. He received his B.S. in physics from Fudan University in 2012, advised by Prof. Xingao Gong and Prof. Hongjun Xiang. He received his Ph.D. in physics from the University of California at Berkeley in 2019, followed as a postdoctoral researcher, both advised by Professor Steven G. Louie. He is broadly interested in developing and applying massively-parallelized computational methods based on many-body quantum theories to study excited-state properties of materials. In 2021, Dr. Li received the APS Nicholas Metropolis Award for Outstanding Doctoral Thesis Work in Computational Physics.