Electron-phonon interaction and pairing mechanism in superconducting Ca-intercalated bilayer graphene

Abstract

Using the ab initio anisotropic Eliashberg theory including Coulomb interactions, we investigate the electron-phonon interaction and the pairing mechanism in the recently-reported superconducting Ca-intercalated bilayer graphene. We find that C6CaC6 can support phonon-mediated superconductivity with a critical temperature Tc = 6.8–8.1 K, in good agreement with experimental data. Our calculations indicate that the low-energy Caxy vibrations are critical to the pairing, and that it should be possible to resolve two distinct superconducting gaps on the electron and hole Fermi surface pockets.

First-principles calculations of the superconducting properties in Li-decorated monolayer graphene within the anisotropic Migdal-Eliashberg formalism

“…The inner region is characterized by a snowflake-like electron pocket intersecting a hexagonal electron pocket, which arises from the mixing of the inner C π * states with the Li s states. These Fermi sheets resemble the Γ-centered Fermi surface observed in Ca and Li intercalated bilayer graphene [17,36]. The outer region also has a snowflake-like shape and originates on the outer C π * states and the Li s states.…”

“…We now focus on the vibrational properties and the electron-phonon coupling (EPC) in LiC 6 . Similar to bulk CaC 6 [32] and bilayer C 6 CaC 6 [17], one can clearly identify in Fig. 2(a) three regions in the phonon dispersion associated to (i) the Li-related modes (up to 50 meV, where above 37 meV are Li z modes mixed with carbon out-of-plane C z modes), (ii) the carbon out-of-plane C z vibrations (50-100 meV), and (iii) the carbon in-plane C xy modes (above 100 meV).…”

Evolution of electronic structure of few-layer phosphorene from angle-resolved photoemission spectroscopy of black phosphorous

“…For N 2, another pocket around the point appears. Such a layer dependence can affect nesting and might lead to layer number dependence in the superconducting properties, similarly to what is expected for few-layer graphene [57].…”

Electron-phonon coupling and pairing mechanism in β−Bi2Pd centrosymmetric superconductor

“…We have recently used this methodology to investigate the superconducting properties of layered and two-dimensional materials with highly anisotropic Fermi surfaces [36][37][38][39]. The electronic wavefunctions required for the Wannier-Fourier inarXiv:1703.03012v1 [cond-mat.supr-con] 8 Mar 2017…”