Superconductivity in lithium under pressure from electron-phonon coupling

ORAL

Abstract

Lithium exhibits a very high superconducting transition temperature at pressures above 20 GPa. To explore the role of phonon induced pairing of the electrons, we apply first principle techniques based on the pseudopotential density functional approach and the Wannier interpolation method to calculate the electron-phonon coupling properties of lithium for the pressure range of 10-40 GPa. We are able to sample a very fine k-point grid with up to several million points in the Brillouin zone (BZ). The Fermi surface (FS) nesting features and phonon renormalizations were examined. Our results for the coupling strengths and phonon linewidths are consistent with previous studies where high resolution was not yet available. The pressure increase results in an increase in the electron-phonon coupling parameter throughout the BZ. We find that the pressure dependent coupling is also related to the shape of the FS. The calculated Tc is in agreement with experiment.

*This work was supported by National Science Foundation Grant No. DMR07-05941, the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Computational resources have been provided by Lawrence Livermore National Laboratory.

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Authors

  • Timur Bazhirov

    • Department of Physics, University of California, Berkeley; Material Science Division, Lawrence Berkeley National Laboratory

  • Jesse Noffsinger

    • Department of Physics, University of California, Berkeley; Material Science Division, Lawrence Berkeley National Laboratory

  • Marvin L. Cohen

    • UC Berkeley and Lawrence Berkeley National Laboratory
    • Department of Physics, University of California, Berkeley. Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California
    • UC Berkeley
    • Department of Physics, University of California, Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory
    • Department of Physics, University of California, Berkeley; Material Science Division, Lawrence Berkeley National Laboratory
    • Deptartment of Physics, University of California, Berkeley; Materials Science Division, Lawrence Berkeley National Laboratory
    • Department of Physics, University of California, Berkeley, and Materials Science Division, Lawrence Berkeley National Laboratory
    • Department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720