First-principles calculation of the superconducting transition in MgB2 within the anisotropic Eliashberg formalism

Hyoung Joon Choi, David Roundy, Hong Sun, Marvin L. Cohen, Steven G. Louie

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Abstract

We present a study of the superconducting transition in MgB2 using the ab initio pseudopotential density- functional method, a fully anisotropic Eliashberg equation, and a conventional estimate for μ*. Our study shows that the anisotropic Eliashberg equation, constructed with ab initio calculated momentum-dependent electron-phonon interaction and anharmonic phonon frequencies, yields an average electron-phonon coupling constant λ=0.61, a transition temperature Tc=39 K, and a boron isotope-effect exponent αB=0.32. The calculated values for Tc, λ, and αB are in excellent agreement with transport, specific-heat, and isotope-effect measurements, respectively. The individual values of the electron-phonon coupling λ(k,k′) on the various pieces of the Fermi surface, however, vary from 0.1 to 2.5. The observed Tc is a result of both the raising effect of anisotropy in the electron-phonon couplings and the lowering effect of anharmonicity in the relevant phonon modes.

Original languageEnglish
Article number020513
Pages (from-to)205131-205134
Number of pages4
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume66
Issue number2
Publication statusPublished - 2002 Jul 1

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All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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