Study of the Two Dimensional Holstein Model using Determinant Quantum Monte Carlo and Migdal-Eliashberg Theory.

ORAL

Abstract

The simplest model for studying electron-phonon coupling in many body systems is the singleband Holstein model. Most studies that utilize this model examine the nature of charge-density and pairing correlations at or around half-filling, but no comprehensive calculation for the dependence of the critical temperatures Tc SC , Tc CDW on the electron occupancy 〈n〉 far away from half-filling seems to exist in the literature. Furthermore, many of these studies compare results from quantum Monte-Carlo (QMC) to Migdal-Eliashberg (ME) theory in an attempt to shed light on the importance of the vertex corrections neglected in ME theory. In this presentation, we will show results highlighting the ME theory phase diagram with respect to 〈n〉over multiple phonon frequencies Ωph using relatively large lattice sizes. Moreover, we will also compare DQMC against ME theory on smaller lattices across a wide range of 〈n〉 and for multiple phonon frequencies. The corresponding ME theory results are found to be comparable to the numerically exact DQMC for lower occupancies (〈n〉≤0.4 ). Lastly, we will discuss the implications of these findings for superconductors with low numbers of charge carriers.

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Presenters

  • Philip Dee

    Physics, Univ of Tennessee, Knoxville

Authors

  • Philip Dee

    Physics, Univ of Tennessee, Knoxville

  • Ken Nakatsukasa

    Physics, Univ of Tennessee, Knoxville

  • Yan Wang

    Physics, University of Sherbrooke, Université de Sherbrooke, Physics, Université de Sherbrooke

  • Benjamin Nosarzewski

    Stanford Univ, Physics, Stanford University

  • Edwin Huang

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

    Univ. of Tennessee, Univ of Tennessee, Physics, Univ of Tennessee, Knoxville, Physics and Astronomy, University of Tennessee, Department of Physics and Astronomy, University of Tennessee, Physics, Univ. of Tennessee, physics and astronomy, University of Tennessee, Department of Physics and Astronomy, Univ of Tennessee, Knoxville