Superconducting transition temperatures of pure vanadium and vanadium-titanium alloys in the presence of dynamical electronic correlations

D. Jones; A. Östlin; A. Weh; F. Beiuşeanu; U. Eckern; L. Vitos; L. Chioncel

doi:10.1103/PhysRevB.109.165107

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Superconducting transition temperatures of pure vanadium and vanadium-titanium alloys in the presence of dynamical electronic correlations

D. Jones, A. Östlin, A. Weh, F. Beiuşeanu, U. Eckern, L. Vitos, L. Chioncel

DOI 10.1103/PhysRevB.109.165107 · Physical Review B

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Abstract

Ordinary superconductors are widely assumed insensitive to small concentrations of random nonmagnetic impurities, whereas strong disorder suppresses superconductivity, ultimately leading to a superconductor-insulator transition. In between these limiting cases, a most fascinating regime may emerge where disorder enhances superconductivity. This effect is discussed here for the β phase of vanadium-titanium alloys. Disorder is modeled using the coherent potential approximation while local electronic interactions are treated using dynamical mean-field theory. The McMillan formula is employed to estimate the superconducting transition temperature, showing a maximum at a Ti concentration of around 0.33 for a local Coulomb interaction U in the range of 2 eV to 3 eV. Our calculations quantitatively agree with the experimentally observed concentration-dependent increase of Tc, and its maximal value of about 20%.