Constraints on the mechanism of superconductivity for MgB 2 from Tc and the total isotope effect

Abstract

We examine the possible electron–phonon spectra that produce both T c=39 K and an isotope coefficient β=0.32±0.01, with Eliashberg theory. We assess the viability of the conventional electron–phonon mechanism in light of these results, compared with ab initio calculations of the electron–phonon spectrum. Comparisons are made with similar considerations for low T c materials.