Superconductivity of amorphous Mg 0.70Zn 0.30−xGa x alloys

Abstract

The screening dependence theoretical investigations of the superconducting state parameters (SSP) viz. electron–phonon coupling strength λ, Coulomb pseudopotential μ ∗, transition temperature T C , isotope effect exponent α and effective interaction strength N O V of five Mg 0.70Zn 0.30− x Ga x ( x = 0.0, 0.06, 0.10, 0.15 and 0.20) ternary amorphous alloys viz. Mg 0.70Zn 0.30Ga 0.00, Mg 0.70Zn 0.24Ga 0.06, Mg 0.70Zn 0.20Ga 0.10, Mg 0.70Zn 0.15Ga 0.15 and Mg 0.70Zn 0.10Ga 0.20 have been reported for the first time using Ashcroft’s empty core (EMC) model potential. Five local field correction functions proposed by Hartree (H), Taylor (T), Ichimaru–Utsumi (IU), Farid et al. (F) and Sarkar et al. (S) are used in the present investigation to study the screening influence on the aforesaid properties. It is observed that the electron–phonon coupling strength λ and the transition temperature T C are quite sensitive to the selection of the local field correction functions, whereas the Coulomb pseudopotential μ ∗, isotope effect exponent α and effective interaction strength N O V show weak dependences on the local field correction functions. The transition temperature T C obtained from H-local field correction function is found in an excellent agreement with available experimental data. Quadratic T C equation has been proposed, which provide successfully the T C values of ternary amorphous alloys under consideration. Also, the present results are found in qualitative agreement with other such earlier reported data, which confirms the superconducting phase in the ternary amorphous alloys.