Strong-coupling superconductivity in CaLi2 under the pressure of 100 GPa

• Superconducting properties of CaLi2 compound at 100 GPa.
• The Eliashberg approach.
• The high critical temperature.
• The non-BCS value of the ratio of the energy gap to the critical temperature.
• The large electron effective mass.

In presented paper the superconducting properties of compressed CaLi2 compounds have been calculated for P21/cP21/c phase. Energy gap, critical temperature and electron effective mass are analyzed within the framework of the strong-coupling Eliashberg theory for a wide range of Coulomb pseudopotential μ⋆∈〈0.1,0.3〉μ⋆∈〈0.1,0.3〉. It has been stated that Δ(0)Δ(0) decreases from 6.01 meV to 3.62 meV, TC decreases from 29.31 K to 18.16 K and dimensionless ratio 2Δ(0)/kBTC2Δ(0)/kBTC decreases from 4.76 to 4.64 dependently on the assumed value of the Coulomb pseudopotential. Moreover, it has been proved, that the ratio of the electron effective mass to the electron band mass me⋆/me is high in the whole range of the superconducting phase existence and reaches its maximum equal to 3.73 for the critical temperature regardless of the value of Coulomb pseudopotential.