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arXiv · 2009.05586

Magnetism and charge order in the honeycomb lattice

Natanael C. Costa·Kazuhiro Seki·Sandro Sorella
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Abstract

Despite being relevant to better understand the properties of honeycomb-like systems, as graphene-based compounds, the electron-phonon interaction is commonly disregarded in theoretical approaches. That is, the effects of phonon fields on \textit{interacting} Dirac electrons is an open issue, in particular when investigating long-range ordering. Thus, here we perform unbiased quantum Monte Carlo simulations to examine the Hubbard-Holstein model (HHM) in the half-filled honeycomb lattice. By performing careful finite-size scaling analysis, we identify semimetal-to-insulator quantum critical points, and determine the behavior of the antiferromagnetic and charge-density wave phase transitions. We have, therefore, established the ground state phase diagram of the HHM for intermediate interaction strength, determining its behavior for different phonon frequencies. Our findings represent a complete description of the model, and may shed light on the emergence of many-body properties in honeycomb-like systems.

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Natanael C. Costa, Kazuhiro Seki, Sandro Sorella. 2020-09-11. Magnetism and charge order in the honeycomb lattice. https://doi.org/10.1103/physrevlett.126.107205

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