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