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Beyond Eliashberg superconductivity in MgB2: anharmonicity, two-phonon scattering, and multiple gaps

Amy Y. Liu·I. I. Mazin·Jens Kortus
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Abstract

Density-functional calculations of the phonon spectrum and electron-phonon coupling in MgB$_2$ are presented. The $E_{2g}$ phonons, which involve in-plane B displacements, couple strongly to the $p_{x,y}$ electronic bands. The isotropic electron-phonon coupling constant is calculated to be about 0.8. Allowing for different order parameters in different bands, the superconducting $λ$ in the clean limit is calculated to be significantly larger. The $E_{2g}$ phonons are strongly anharmonic, and the non-linear contribution to the coupling between the $E_{2g}$ modes and the p$_{x,y}$ bands is significant.

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Amy Y. Liu, I. I. Mazin, Jens Kortus. 2001-03-27. Beyond Eliashberg superconductivity in MgB2: anharmonicity, two-phonon scattering, and multiple gaps. https://doi.org/10.1103/physrevlett.87.087005

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