Migdal-Eliashberg theory of multi-band high-temperature superconductivity in field-effect-doped hydrogenated (111) diamond

Abstract

We perform single-and multi-band Migdal-Eliashberg (ME) calculations with parameters exctracted from density functional theory (DFT) simulations to study superconductivity in the electricfield-induced 2-dimensional hole gas at the hydrogenated (111) diamond surface. We show that according to the Eliashberg theory it is possible to induce a high-Tc superconducting phase when the system is field-effect doped to a surface hole concentration of 6 × 10 14 cm −2 , where the Fermi level crosses three valence bands. Starting from the band-resolved electron-phonon spectral functions α 2 F jj (ω) computed ab initio, we iteratively solve the self-consistent isotropic Migdal-Eliashberg equations, in both the single-band and the multi-band formulations, in the approximation of a constant density of states at the Fermi level. In the single-band formulation, we find Tc ≈ 40 K, which is enhanced between 4% and 8% when the multi-band nature of the system is taken into account. We also compute the multi-band-sensistive quasiparticle density of states to act as a guideline for future experimental works.

Strong band-filling-dependence of the scattering lifetime in gated MoS2 nanolayers induced by the opening of intervalley scattering channels

“…Recent developments in density functional theory (DFT) allow computing the electronic 29,30,36 and vibrational 37 properties of materials in the FET configuration from first principles by fully taking into account the presence of an orthogonal electric field in a self-consistent way. In such a way, it has been possible to obtain the electronic structure of many gated TMDs 29,30 , to study the flexural phonons in graphene 37 , to explore the anomalous screening of an electric field at the surface of niobium nitride 38 and to predict a possible high-T c SC phase transition in diamond thin films 39,40 .…”