Nonadiabatic superconductivity in Li-intercalated hexagonal boron nitride bilayer
Abstract
In the case of Li-intercalated hexagonal boron nitride bilayer (Li-hBN), the vertex corrections of electron-phonon interaction cannot be omitted. This is evidenced by the very high value of the ratio λωD/F 0.46, where λ is the electron-phonon coupling constant, ωD is the Debye frequency, and the symbol F represents the Fermi energy. Due to the nonadiabatic effects, the phonon-induced superconducting state in Li-hBN is characterized by the much lower value of critical temperature (T LOVCC∈\ 19.1, 15.5, 11.8\ K, for μ∈ \0.1, 0.14, 0.2\), than would result from calculations not taking this effect into account: T MEC∈\ 31.9, 26.9, 21\ K. From the technological point of view, the low value of TC limits the possible applications of Li-hBN superconducting properties. The calculations were carried out under the classic Migdal-Eliashberg formalism (ME) and the Eliashberg theory with the lowest-order vertex corrections (LOVC).