Small Fermi energy, strong electron–phonon effects and anharmonicity in MgB2

✍ Scribed by E. Cappelluti; L. Pietronero

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 174 KB
• Volume: 460-462
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/j.physc.2007.03.068

✦ Synopsis

The investigation of the electron-phonon properties in MgB 2 has attracted a huge interest after the discovery of superconductivity with T c = 39 K in this compound. Although superconductivity is often described in terms of the conventional Eliashberg theory, properly generalized in the multiband/multigap scenario, important features distinguish MgB 2 from other conventional strong-coupling superconductors. Most important it is the fact that a large part of the total electron-phonon strength seems to be concentrated here in only one phonon mode, the boron-boron E 2g stretching mode. Another interesting property is the small Fermi energy of the r bands, which are strongly coupled with the E 2g mode. In this contribution, we discuss how the coexistence of both these features give rise to an unconventional phenomenology of the electron-phonon properties.