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arXiv:1902.08616 · Physical review. B./Physical review. B

Fermionic multicriticality near Kekulé valence-bond ordering on a honeycomb lattice

Bitan Roy, Vladimir Juričić

Published Jun 5, 2019• 17 citations
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Abstract

We analyze the possibility of emergent quantum multicritical points (MCPs) with enlarged chiral symmetry, when strongly interacting gapless Dirac fermions acquire a comparable propensity toward the nucleation of Kekul\'e valence-bond solid (KVBS) and charge-density-wave (${N}_{b}=1$) or $s$-wave pairing (${N}_{b}=2$) or antiferromagnet (${N}_{b}=3$) in a honeycomb lattice, where ${N}_{b}$ counts the number of bosonic order-parameter components. Besides the cubic terms present in the order-parameter description of KVBS due to the breaking of a discrete ${Z}_{3}$ symmetry, quantum fluctuations generate new cubic vertices near the high-symmetry MCPs. All cubic terms are strongly relevant at the bare level near three spatial dimensions, about which we perform a leading-order renormalization group analysis of coupled Gross-Neveu-Yukawa field theory. We show that due to nontrivial Yukawa interactions among gapless bosonic and fermionic degrees of freedom, all cubic terms ultimately become irrelevant at an $O(2+{N}_{b})$ symmetric MCP, at leas near two spatial dimensions, where ${N}_{b}=1,2,3$. Therefore, MCPs with an enlarged $O(2+{N}_{b})$ symmetry near KVBS ordering are stable.

DOI
10.1103/physrevb.99.241103

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