The phonon-mediated superconductivity in B2CB2C sheet

The values of the thermodynamic parameters of the superconducting state induced by the electron–phonon interaction in the B2CB2C sheet have been determined. It has been found that the critical temperature (TC) can change in the range from 20.4 K to 13 K for the Coulomb pseudopotential (μ⋆)(μ⋆) ranging from 0.1 to 0.2. Generalization of the results for the atomic layer demonstrated that the maximum value of TC is equal to 25 K. Next for the B2CB2C sheet, the order parameter (Δ), the thermodynamic critical field (HC), and the specific heat for the superconducting (CS) state and the normal (CN) state have been calculated. The obtained results show that the dimensionless thermodynamic ratios, RΔ≡2Δ(0)/kBTCRΔ≡2Δ(0)/kBTC, RH≡TCCN(TC)/HC2(0), and RC≡(CS(TC)−CN(TC))/CN(TC)RC≡(CS(TC)−CN(TC))/CN(TC), deviate from the predictions of the classical BCS theory. In particular RΔ(μ⋆)∈〈3.87,3.79〉RΔ(μ⋆)∈〈3.87,3.79〉, RH(μ⋆)∈〈0.155,0.157〉RH(μ⋆)∈〈0.155,0.157〉, and RC(μ⋆)∈〈1.67,1.62〉RC(μ⋆)∈〈1.67,1.62〉. The numerical calculations have been conducted in the framework of the Eliashberg formalism.