First-principles calculation of the superconducting transition in MgB2 within the anisotropic Eliashberg formalism
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 mu*. 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 lambda = 0.61, a transition temperature T-sub c = 39 K, and a boron isotope-effect exponent alpha-sub B = 0.32. The calculated values for T-sub c, lambda, and alpha-sub B are in excellent agreement with transport, specific-heat,and isotope-effect measurements, respectively. The individual values of the electron-phonon coupling lambda (k,k-prime) on the various pieces of the Fermi surface, however, vary from 0.1 to 2.5. The observed T-sub c 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.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Director, Office of Science. Office of Basic Energy Studies. Materials Science and Engineering Division; National Science Foundation (US)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 805159
- Report Number(s):
- LBNL-51640; R&D Project: 506701; B& R KC0202030; TRN: US0301671
- Journal Information:
- Physical Review B, Vol. 66, Issue 2; Other Information: Journal Publication Date: July 1, 2002; PBD: 6 Jun 2002
- Country of Publication:
- United States
- Language:
- English
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