We present a framework for the anisotropic Eliashberg theory for the superconducting properties of MgB2 and reduce the framework to a zeroth-order two-band model by neglecting the variation of the electron-phonon interaction within the σ and π sheets, of the Fermi surface. We then derive a second-order-corrected two-band model using a systematic expansion of the theory with respect to the intrasheet variation of the electron-phonon interaction. Our results show that the zeroth-order two-band model reproduces successfully the results of the anisotropic Eliashberg theory with fairly small errors and that, with the second-order corrections, the model coincides with the full theory. The second-order-corrected two-band model reproduces not only the intersheet but also the intrasheet variation of the superconducting energy gap on the Fermi surface.
|Physical Review B - Condensed Matter and Materials Physics
|Published - 2006
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics