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arXiv · 1709.02289

Antiferromagnetism and competing charge instabilities of electrons in strained graphene from Coulomb interactions

David Sánchez de la Peña·Julian Lichtenstein·Carsten Honerkamp·Michael M. Scherer
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Abstract

We study the quantum many-body ground states of electrons on the half-filled honeycomb lattice with short- and long-ranged density-density interactions as a model for graphene. To this end, we employ the recently developed truncated-unity functional renormalization group (TU-fRG) approach which allows for a high resolution of the interaction vertex' wavevector dependence. We connect to previous lattice quantum Monte Carlo (QMC) results which predict a stabilization of the semimetallic phase for realistic \emph{ab initio} interaction parameters and confirm that the application of a finite biaxial strain can induce a quantum phase transition towards an ordered ground state. In contrast to lattice QMC simulations, the TU-fRG is not limited in the choice of tight-binding and interaction parameters to avoid the occurrence of a sign problem. Therefore, we also investigate a range of parameters relevant to the realistic graphene material which are not accessible by numerically exact methods. Although a plethora of charge density waves arise under medium-range interactions, we find the antiferromagnetic spin-density wave to be the prevailing instability for long-range interactions. We further explore the impact of an extended tight-binding Hamiltonian with second-nearest neighbor hopping and a finite chemical potential for a more accurate description of the band structure of graphene's $p_z$ electrons.

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David Sánchez de la Peña, Julian Lichtenstein, Carsten Honerkamp, Michael M. Scherer. 2017-10-05. Antiferromagnetism and competing charge instabilities of electrons in strained graphene from Coulomb interactions. https://doi.org/10.1103/physrevb.96.205155

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