Charge density wave and superconducting phase in monolayer InSe

In this paper, the completed investigation of a possible superconducting phase in monolayer indium selenide is determined using first-principles calculations for both the hole and electron doping systems. The hole-doped dependence of the Fermi surface is exclusively fundamental for monolayer InSe. It leads to the extensive modification of the Fermi surface from six separated pockets to two pockets by increasing the hole densities. For low hole doping levels of the system, below the Lifshitz transition point, superconductive critical temperatures ${T}_{c}\ensuremath{\sim}55--75$ K are obtained within anisotropic Eliashberg theory depending on varying amounts of the Coulomb potential from 0.2 to 0.1. However, for some hole doping above the Lifshitz transition point, the combination of the temperature dependence of the bare susceptibility and the strong electron-phonon interaction gives rise to a charge density wave that emerged at a temperature far above the corresponding ${T}_{c}$. Having included nonadiabatic effects, we could carefully analyze conditions for which either a superconductive or charge density wave phase occurs in the system. In addition, monolayer InSe becomes dynamically stable by including nonadiabatic effects for different carrier concentrations at room temperature.