Electron-phonon interaction in the normal and superconducting states of MgB 2
By Yong Kong, O. Dolgov, O. Jepsen, O. K. Andersen. 2001
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For the 40K-superconductor MgB2 we have calculated the electronic and phononic structures and the electron-phonon interaction throughout the Brillouin zone ab initio. In contrast to the isoelectronic graphite, MgB2 has holes in the bonding sigma-bands, which contribute 42 per cent to the density of states: N(0) =0.355 states/(MgB2 eV spin). The total interaction strength, lambda =0.87 and lambda,tr=0.60, is dominated by the coupling of the sigma-holes to the bond-stretching optical phonons with wavenumbers in a narrow range around 590 cm^{-1}. Like the holes, these phonons are quasi two-dimensional and have wave-vectors close to Gamma-A, where their symmetry is E. The pi-electrons contribute merely 0.25 to lambda and to lambda,tr. With Eliashberg theory we evaluate the normal-state resistivity, the density of states in the superconductor, and the B-isotope effect on Tc and Delta0, and find excellent agreement with experiments, when available. Tc=40 K is reproduced with mu*=0.10 and 2Delta0/kB Tc=3.9. MgB2 thus seems to be an intermediate-coupling e-ph pairing s-wave superconductor.
Subfields: Condensed Matter Physics, Electronic, Optical and Magnetic Materials
View Paper: https://www.semanticscholar.org/paper/188cd4c79afb16f4dc92655b33859bc90a9c1a73
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In Condensed Matter Physics
In Electronic, Optical and Magnetic Materials
Citations in the corpus
- Ultrafast optical spectroscopy of strongly correlated materials and high-temperature superconductors: a non-equilibrium approach (2016, background): “Right panel: phonon dispersion and density of states and bosonic function calculated for MgB2 [98].”