Interplay of electron-phonon interaction and electron correlation in high-temperature superconductivity

Electron -phonon Superconductivity

Electron-phonon interactions and superconductivity.

A NUMERICAL RENORMALIZATION GROUP APPROACH FOR AN ELECTRON-PHONON INTERACTION

A finite chain calculation in terms of Hubbard X-operators is explored by setting up a vibronic Harniltonian. The model conveniently transformed into a form so that in the case of strong coupling a numerical renormalization group approach is applicable. To test the technique, a one particle Green function is calculated for the model Harniltonian

Competing phases, strong electron-phonon interaction, and superconductivity in elemental calcium under high pressure

The observed “simple cubic” sc phase of elemental Ca at room temperature in the 32–109 GPa range is, from linear-response calculations, dynamically unstable. By comparing first-principles calculations of the enthalpy for five sc-related nonclose-packed structures, we find that all five structures compete energetically at room temperature in the 40–90 GPa range, and three do so in the 100–130 GP...

d-wave superconductivity from electron-phonon interactions

I examine electron-phonon mediated superconductivity in the intermediate coupling and phonon frequency regime of the quasi-2D Holstein model. I use an extended Migdal–Eliashberg theory which includes vertex corrections and spatial fluctuations. I find a d-wave superconducting state that is unique close to half-filling. The order parameter undergoes a transition to s-wave superconductivity on in...