The frustrated Heisenberg antiferromagnet on the honeycomb lattice: A candidate for deconfined quantum criticality

TL;DR

This study maps the phase diagram of a frustrated spin-1/2 honeycomb lattice model, identifying a continuous transition suggestive of deconfined quantum criticality between Ne9el and PVBC phases.

Contribution

It provides the first detailed analysis indicating a deconfined quantum critical point in the honeycomb lattice J1-J2-J3 model using coupled-cluster and exact diagonalization methods.

Findings

Identifies Ne9el, PVBC, and striped AFM phases.

Finds a continuous transition at a7_{c_1} e280a7e2a4.

Suggests deconfined quantum criticality at the Ne9el-PVBC transition.

Abstract

We study the ground-state (gs) phase diagram of the frustrated spin-1/2 $J_{1}$-$J_{2}$-$J_{3}$ antiferromagnet with $J_{2} = J_{3} =\kappa J_1$ on the honeycomb lattice, using coupled-cluster theory and exact diagonalization methods. We present results for the gs energy, magnetic order parameter, spin-spin correlation function, and plaquette valence-bond crystal (PVBC) susceptibility. We find a N\'eel antiferromagnetic (AFM) phase for $\kappa < \kappa_{c_{1}} \approx 0.47$, a collinear striped AFM phase for $\kappa > \kappa_{c_{2}} \approx 0.60$, and a paramagnetic PVBC phase for $\kappa_{c_{1}} \lesssim \kappa \lesssim \kappa_{c_{2}}$. The transition at $\kappa_{c_{2}}$ appears to be of first-order type, while that at $\kappa_{c_{1}}$ is continuous. Since the N\'eel and PVBC phases break different symmetries our results favor the deconfinement scenario for the transition at $\kappa_{c_{1}}$.