Instabilities on graphene's honeycomb lattice with electron-phonon interactions

Laura Classen, Michael M. Scherer, and Carsten Honerkamp
Phys. Rev. B 90, 035122 – Published 17 July 2014

Abstract

We study the impact of electron-phonon interactions on the many-body instabilities of electrons on the honeycomb lattice and their interplay with repulsive local and nonlocal Coulomb interactions at charge neutrality. To that end, we consider in-plane optical phonon modes with wave vectors close to the Γ point as well as to the K,K points and calculate the effective phonon-mediated electron-electron interaction by integrating out the phonon modes. Ordering tendencies are studied by means of a momentum-resolved functional renormalization-group approach allowing for an unbiased investigation of the appearing instabilities. In the case of an exclusive and supercritical phonon-mediated interaction, we find a Kekulé and a nematic bond ordering tendency being favored over the s-wave superconducting state. The competition between the different phonon-induced orderings clearly shows a repulsive interaction between phonons at small- and large-wave-vector transfers. We further discuss the influence of phonon-mediated interactions on electronically driven instabilities induced by on-site, nearest-neighbor, and next-nearest-neighbor density-density interactions. We find an extension of the parameter regime of the spin-density-wave order going along with an increase of the critical scales where ordering occurs and a suppression of competing orders.

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  • Received 2 May 2014
  • Revised 25 June 2014

DOI:https://doi.org/10.1103/PhysRevB.90.035122

©2014 American Physical Society

Authors & Affiliations

Laura Classen1,*, Michael M. Scherer1,†, and Carsten Honerkamp2,‡

  • 1Institut für Theoretische Physik, Universität Heidelberg, 69120 Heidelberg, Germany
  • 2Institute for Theoretical Solid State Physics, RWTH Aachen University, 52062 Aachen, Germany and Jülich Aachen Research Alliance, Fundamentals of Future Information Technology, 52382 Jülich, Germany

  • *classen@thphys.uni-heidelberg.de
  • scherer@thphys.uni-heidelberg.de
  • honerkamp@physik.rwth-aachen.de

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Issue

Vol. 90, Iss. 3 — 15 July 2014

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