Etude de supraconductivité de l’alliage 𝑴𝒈𝟏_𝒙𝑪𝒅𝒙𝑪𝑵�

Abstract

This work aims to study the structural and superconducting properties of the alloy depending on the concentration of the atom of Cadmium Cd, using first-principles calculations. Our calculations were performed by the pseudo-potentials method and the density functional theory (DFT) within the generalized gradient approximation (GGA) for the treatment of the exchange and correlation term, and the virtual crystal approximation (VCA). The results obtained from the study of structural properties shows that the lattice parameter 𝑎0 decreases with increasing Cd atom concentration from 0 to 0.5 and increases from 0.5 to 1 . The calculated bulk modulus 𝐵 shows an opposite relation between a0 and B. Concerning the study of superconductivity, we have calculated the Eliashberg function 𝛼 2𝐹(𝜔), and we have focused our attention on the comparison between the phonon density DOS. The electron-phonon coupling constant λ and the critical temperature 𝑇𝑐 are calculated and evaluated in function of concentration (x) of the Cd atom, It was concluded that the increase of λ as a function of concentration leads to the increase of 𝑇𝑐 . Our results are in disagreement with experimental ones, this is because the negative phonon frequency calculated. All the obtained results are compared with the theoretical and observed data available in the literature.