Lithium doping effects on phonon and electron-phonon properties of Bi₂Sr₂CaCu₂O₈

Cuprate metal oxides are known for their unconventional high-temperature superconductivity, the details of which remain a subject of ongoing research and discussion. Within the established BCS theory and its generalization made by Eliashberg, the introduction of high-frequency phonons, e.g. by doping light elements like lithium, can lead to higher superconducting transition temperature. Drawing on these ideas, our study explores the effects of introducing light elements into cuprates and focuses on their impact on phonon modes and electron-phonon interactions. Using density functional theory, we’ve selected Bi₂Sr₂CaCu₂O₈ (BSCCO, Bi-2212) as a prototypical cuprate and investigated how lithium doping affects its phononic and electron-phonon properties. We present an analysis on atom, mode, and layer-resolved electron-phonon coupling for Li-Bi substitution.