Electron-phonon coupling and two-band superconductivity of Al- and C-doped MgB2

O. De la Peña-Seaman, R. de Coss, R. Heid, and K.-P. Bohnen
Phys. Rev. B 82, 224508 – Published 10 December 2010

Abstract

We have studied the electron-phonon and superconducting properties of the Mg1xAlxB2 and MgB2(1y)C2y alloys within the framework of density-functional theory using the self-consistent virtual-crystal approximation. For both alloys, the Eliashberg spectral functions and the electron-phonon coupling constants have been calculated in the two-band model for several concentrations up to x(Al)=0.55 and y(C)=0.175. We solved numerically the two-band Eliashberg gap equations without considering interband scattering. Using a single parameter for the Coulomb pseudopotential, which was determined for the undoped compound, we were able to reproduce the experimental doping dependence of Δσ, Δπ, and Tc for both alloys on a quantitative level. In particular, the observed differences in the doping range of superconductivity between Al and C doping indicate a pronounced influence of the doping site, which can be explained naturally in the present approach without the need to invoke interband scattering, suggesting that this factor plays only a minor role.

    • Received 1 July 2010

    DOI:https://doi.org/10.1103/PhysRevB.82.224508

    ©2010 The American Physical Society

    Authors & Affiliations

    O. De la Peña-Seaman1,2, R. de Coss1, R. Heid2, and K.-P. Bohnen2

    • 1Departamento de Física Aplicada, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 73, Cordemex, 97310 Mérida, Yucatán, Mexico
    • 2Institut für Festkörperphysik, Karlsruher Institut für Technologie (KIT), P.O. Box 3640, D-76021 Karlsruhe, Germany

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    Issue

    Vol. 82, Iss. 22 — 1 December 2010

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