Breakdown of Migdal-Eliashberg theory; a Quantum Monte Carlo study

ORAL

Abstract

The superconducting (SC) and charge-density-wave (CDW) susceptibilities of the two dimensional Holstein model are computed using Determinental Quantum Monte Carlo (DQMC), and compared with results computed using the Migdal-Eliashberg (ME) approach. We access temperatures as low as 20 times less than the Fermi energy, $E_F$, which are still above the SC transition. We find that the SC susceptibility at low $T$ agrees quantitatively with the ME theory up to a dimensionless electron-phonon coupling $\lambda_0 \approx 0.4$ but deviates dramatically for larger $\lambda_0$. We find that for large $\lambda_0$ and small phonon frequency $\omega_0 \ll E_F$ CDW ordering is favored and the preferred CDW ordering vector is uncorrelated with any obvious feature of the Fermi surface.

–

Presenters

  • Ilya Esterlis

    • Stanford Univ
    • Physics, Stanford University

Authors

  • Ilya Esterlis

    • Stanford Univ
    • Physics, Stanford University

  • Benjamin Nosarzewski

    • Stanford Univ
    • Physics, Stanford University

  • Edwin Huang

    • Stanford Univ
    • SLAC National Accelerator Laboratory
    • Physics, Stanford University
    • Stanford University

  • Brian Moritz

    • Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory
    • SLAC - Natl Accelerator Lab
    • SLAC and Stanford University
    • SLAC National Accelerator Laboratory
    • Stanford Institute for Materials and Energy Sciences, SLAC National Laboratory
    • SIMIS, Stanford University
    • Physics, Stanford University
    • Stanford Univ
    • SIMES, SLAC and Stanford University

  • Thomas Devereaux

    • Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory
    • Stanford Univ
    • SLAC and Stanford University
    • SLAC National Accelerator Laboratory
    • SLAC - Natl Accelerator Lab
    • Stanford Institute for Materials and Energy Sciences, SLAC National Laboratory
    • Stanford University
    • SIMIS, Stanford University
    • Physics, Stanford University
    • SLAC National Lab and Stanford University
    • SIMES, SLAC and Stanford University

  • Steven Kivelson

    • Stanford University
    • Stanford Univ
    • Physics, Stanford University

  • Douglas Scalapino

    • physics, Univ of California - Santa Barbara
    • Physics, UCSB
    • University of California, Santa Barbara