First-Principles Study of Superconductivity in Ultra- thin Pb Films

ORAL

Abstract

Recently, superconductivity in ultrathin layered Pb has been confirmed in samples with as few as two atomic layers [S. Qin, J. Kim, Q. Niu, and C.-K. Shih, Science 2009]. Interestingly, the prototypical strong-coupling superconductor exhibits different $T_c$'s for differing surface reconstructions in samples with only two monolayers. Additionally, $T_c$ is seen to oscillate as the number of atomic layers is increased. Using first principles techniques based on Wannier functions, we analyze the electronic structure, lattice dynamics and electron-phonon coupling for varying thicknesses and surface reconstructions of layered Pb. We discuss results as they relate to superconductivity in the bulk, for which accurate calculations of superconducting properties can be compared to experiment [W. L. McMillan and J.M. Rowell, PRL 1965]. 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 the Lawrencium computational cluster resource provided by the IT Division at the Lawrence Berkeley National Laboratory (Supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231)

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Authors

  • Jesse Noffsinger

    Deptartment of Physics, University of California, Berkeley; Materials 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