Electron–phonon coupling and superconductivity in a 2D Tl–Pb compound on Si(111)

Physical Chemistry Chemical Physics. 2022. Vol. 24. No. 17. P. 10140–10146.

Sklyadneva I. Y., Heid R., Echenique P. M., E. V. Chulkov

Electron–phonon interaction in a single-layer Tl–Pb compound on Si(111) is investigated within the densityfunctional
theory and linear-response approach in the mixed-basis pseudopotential representation. It is found
that phonon-induced scattering of electrons at the Fermi level is primarily determined by surface electronic
states responsible for bonding at the interface and by low-energy, predominantly shear-vertical vibrations of
adatoms. The contribution of substrate-localized vibrations involved in the electron–phonon scattering turns out
to be small. We have also estimated the superconducting transition temperature Tc by solving the linearized gap
equation of the Eliashberg theory. An analysis of phonon-mediated transitions for a number of electronic states
in the Tl–Pb surface bands showed that the strength of the coupling varies with the binding energy, increasing
as it approaches the Fermi level, and significantly depends on the surface band to which the state belongs.

Keywords: superconductivity, Density functional theory (DFT), Electron–phonon coupling, Eliashberg theory