Phonon dispersion and lifetimes in MgB2

TL;DR

This study combines experimental inelastic X-Ray scattering and theoretical Density Functional Theory calculations to analyze phonon dispersion and linewidth in MgB2, revealing electron-phonon coupling as the main broadening mechanism.

Contribution

It provides a detailed experimental and theoretical investigation of phonon properties in MgB2, highlighting the role of electron-phonon interactions and anharmonicity.

Findings

Anomalous broadening of the E_2g phonon mode along Gamma-A.

Excellent agreement between experiment and DFT calculations.

Electron-phonon coupling is the dominant contributor to phonon linewidth.

Abstract

We measure phonon dispersion and linewidth in a single crystal of MgB_2 along the Gamma-A, Gamma-M and A-L directions using inelastic X-Ray scattering. We use Density Functional Theory to compute the effect of both electron-phonon coupling and anharmonicity on the linewidth, obtaining excellent agreement with experiment. Anomalous broadening of the E_2g phonon mode is found all along Gamma-A. The dominant contribution to the linewidth is always the electron-phonon coupling.